This happened a couple years back. My gf, her sister, her mom and I all went to a cabin we booked for the weekend. This was the first time I was meeting her sister. My gf told me her sister was different and somewhat of a free spirit but she didn't elaborate. I drove up with my gf and picked up her mom on the way. Her sister Ann was going to meet us there. We arrived before Ann and unpacked. There were 3 rooms in the cabin which worked out perfect. A few minutes after we had got all our stuff brought in Ann showed up. She is as around 5'2", curly brown hair, bright blue eyes, a nice curvy frame to her, pert tight ass and some very nice breasts. I was really surprised when I first seen her, she was way more attractive then her sister. I introduced myself to her and she said hi with a beautiful smile back to me. I offered to help her bring her things in and helped her her settled. Every did their hellos and we all sat down for a bit. It was getting close to lunch time and my gfs mom offered to run into town and get us some food. My gf, Ann and I all stayed behind. Town was about a 20 minute drive. My gf asked what we should do to pass the time. Ann mentioned she noticed the dock when she pulled in and suggested we all go for a swim on the hot summer day. We all agreed and went and changed into our swim suits. My gf and I were down at the lake first and both jumped in. The water was a little cold for how hot it was. I seen Ann walking down the dock and couldn't help but stare a bit. She had on a black bikini with slits cut in the top and a very small black thong to go with it. I made sure not to stare too long didn't want to get in trouble. Ann had brought down some towels for us to use as well. Ann jumped in with us and it was pretty laid back. We swam around for about 10 minutes and then Ann said she was going to tan on the dock until her mom got back, my girlfriend said she would join her. I kept swimming in the lake. Once Ann was up on the dock she pulled off her bikini top and dropped her thong down. I couldn't believe what was happening. Ann had an amazing body, her tits were perky and round and had a nicely shaved pussy. I looked at my gf right as she was turning to look at me. She had this really annoyed look on her face as she knew I had seen her sister naked. My gf looked at Ann and said you don't need to be naked to tan. Ann said it wasn't a big deal and didn't want tan lines. She laid out, face up, on the towel with her head towards the end of dock. My gf laid down next to her but left her bikini on, I was kind of hoping to see them both naked. I continued to swim but couldn't get the image of her sister out of my head. I was so hard in my swim suit, I had to adjust myself. The head of my dick was sticking out the top of my trunks. I decided I was going to get out of the lake and go shower quick before dinner. I went to beach and walked up. I walked out to the dock and Ann sat up. I got to see her very nice breasts up close. She looked at me and then at my crotch and got a little smile on her face. She looked at me, my crotch and back to me. I knew she had seen I was hard and my head of my cock was sticking out. She slowly turned over onto her stomach and slightly arched her butt as she did. I got a very nice view of her pussy and ass when she did this. I told my gf I was going to shower and quickly turned so she wouldn't see my boner. I really wanted to bust one out in the shower but figured I could just bang my gf later. After I got out of the shower, the girls mom got back. I got dressed and came out to help her. The girls came back up and changed clothes and we grilled outside. The girls were both wearing tank tops and jean shorts. We grilled up the food quick and all sat around the fire pit to eat. As we were eating I kept seeing Ann eyeing me up I thought. We finished dinner and then started a fire. We made some mixed drinks and all sat around the fire to hang out. My gf was really clingy when she was drinking and tonight was no exception. I couldn't really check out Ann as it would have been too obvious. Once it got dark we moved inside to the table to play cards and drink. we played for quite a while until the girls started to argue over almost nothing it seemed. They got pretty vulgar with one another and I told my gf it was time for bed. She was pretty drunk so I helped her into the bedroom. She said she wanted to lay down as the room was spinning. I helped her into bed and tucked her in. She was out almost in an instant. I wanted to use the bathroom quick before going to bed myself. I closed our bedroom door and walked down the hallway. The bathroom door was closed so I hung out for a bit. When the door opened it was Ann. I said hi and apologized for the things my gf had said to her. Ann said it was no biggie. She told me to have a good night and smiled as she walked away. I used the bathroom quick. When I came out Ann was just walking out of her door. She was completely naked. I couldn't help but stare or hide that I was. I looked up and down her body and made eye contact with her. She had a very seductive smile on her face as she walked by. I swear she was making her ass shake for me as she walked by into the bathroom. She did not close the door and I stood there and watched. She went over to the sink and was brushing her teeth. Her boobs were shaking and swaying as she did. When she was done she bent over towards me and spit out the toothpaste. I got a very clear shot of her pussy again. I was rock hard again in my pants. She walked by and looked down at my pants and saw I was hard. She had a very big smile on her face. She walked into her room slowly and then turned closing the door slowly, starring at my dick the whole time. I stood there for a minute deciding what I should do and figured I should go to bed as she had closed her door. I went and joined my gf in. I really wanted to fuck her but she was passed out so I just went to bed. I woke up fairly early in the morning as I usually do and went out to make us breakfast. I was just in shorts and a Tshirt. I just had cracked the eggs when Ann walked out. She had on a robe this morning which was dissappinting. She asked if she could help and I said yes. She set the table and helped get the bacon out. I was mixing the eggs, when Ann said she was going to shower quick. She had that smile on her face again when she said that. She started to walk towards her room and dropped her robe right outside her door. I watched as her naked body walked into her room. I stood there for a minute thinking what I should do, then I just started walking. I went over and grabbed her robe off the floor and walked into her bedroom. She was bent over getting clothes from her bag. I stood there enjoying the view for a minute. I commented I had got her robe for her. Ann looked back at me with a smile and said thank you. She asked if I could hang it on the door in the bathroom. I slowly backed out of her room making sure to eye her up before I left. I went into the bathroom and hung up the robe on the back of the door. When I opened up the door Ann stood in front of me still naked. She walked by me into the bathroom and put her clothes on the sink counter. I was still like a rock and there was no hiding it. Ann opend the shower door and asked if I could close the bathroom door. I made sure to take one last look before I went out and closed the door. I heard her start the shower and I went back to my room. My gf was still passed out. I grabbed some clothes to take a shower with and walked out and closed the door. I set the clothes on the couch and went to finish breakfast. I had an idea that since she kept walking around me naked I would do the same and see her reaction. A few minutes later I heard the shower turn off and I went and stripped down naked and stood in front of the door waiting, my dick was so hard thinking about her. After a minute I heard her walking towards the door and she opened it in her robe. She was surprised to see me, especially naked. Her eyes immediately went down to my hard cock. She starred at it for a few seconds and then asked what I was doing. I said I was going to shower, she got a slight smile on her face. I asked if she could get my clothes off the couch for me. She said sure and made sure to look at my cock once more before she walked away. She came back with my clothes and set them on the counter for me. She kept starring at my cock. I asked what she was thinking. She looked up at me and said she should probably let me shower and walked out and closed the door. I was dissappinted, I thought maybe she would have wanted to fool around. I got showered and dressed and came out. I finished making breakfast and filled all the plates up. Ann was the first one to come sit down. She had on jean shorts and a low cut Tshirt. I went and woke up my gf who was super hung over. She got up and woke up her mom. We all sat down for breakfast and then my gf wanted to go back to bed. Her mom said she wasn't feeling that well either and said she was going to do the same. Ann and I sat there and finished our breakfast. She asked what my plans were for the day. I said I was thinking of going hiking a little this morning and maybe do some kayaking later. She asked if she could join me and I said yes. I went and grabbed my backpack and hiking shoes. Ann came out with a backpack on and said she was ready to go. We walked down the driveway a bit and there was a trail there. We went on the trail for a way and then it looped back. We got back to the cabin around 11. My gf was laying on the couch and her mom was washing the dishes. My gf opened her eyes and I got a very dirty look. She asked where we had been and Ann said we just went for a quick hike. Ann headed to her room and I went and say next to my gf. She laid her head on my lap and closed her eyes again. My gfs mom said she was going to go out kayaking and asked if we wanted to join. My gf said no she was still too hung over. My gf asked for Advil or ibuprofen but none of us had any. I said I could run into town quick and get some. My gf said that would be great and asked me to help her to bed. I brought her in and tucked her in the bed. I went and got the keys and headed out the door. Ann was standing outside and said she wanted to come with to pick up a couple things. I thought about letting my gf know but she seemed so mad the last time Ann and I did something so I decided not to. We got in the vehicle and headed to town. We had a really good conversation. We stopped at the store and grabbed a couple things and then left. After driving for a few minutes she asked if she could ask me a question. I said sure. Ann asked me if I thought she was attractive. I wanted to say hell yes but acted like I had to think for a minute then said yes. I asked her why she asked that. Ann said she thought I was very attractive and was jealous of her sister. I laughed a little and said why's that. Ann said because she got me all to herself and I probably wanted to fuck her sister every night. Hearing Ann talk like that was getting me hard. I said we didn't have sex as much I wish we could. Ann said I bet that's tough. She then said if she was dating me she would be fucking me all the time and mentioned she couldn't believe how big I was. I asked if her and her sister talked about our sex life much. Ann said she mentioned it briefly and said I always wanted to have sex but her sister didn't. I said that is absolutely correct. I wasn't sure what was going on with her but she never wanted to have sex anymore. Ann asked when was the last time we had sex and I said about 3 weeks ago. She said that sucks. Ann blurted out her sister probably was cheating on me. I asked why she said that. Ann said every guy her sister has ever dated she has cheated on. I said well maybe that's what's going on. It was kind of quiet for bit then Ann asked if I thought she was hotter than her sister, she said to be honest. I said I thought she was. Ann had a big smile on her face. I decided to ask Ann some questions. I asked Ann if she was dating anyone. Ann said yes she had a bf back home. I asked how their sex life was. Ann explained it wasn't that great. He was always on the road for work and they would get to have sex maybe 2 times a month, if they were lucky. I asked when the last time they had sex was. Ann said well over 2 months ago. She then said all the talk about sex was getting her all turned on and maybe we should change the subject before she ended up doing something about it. I asked is that something that she wanted to do. Ann smiled at me and said the thought crossed her mind the first time she saw me. I said that's funny because I had the same thought. She smiled and then bit her lip. She said she had thought about fucking me in the bathroom when I was naked but she was afraid she would get caught. I said it would be fun to sneak off and fool around wouldn't it. Her response surprised me, she asked do you think we have time and that it would have to be quick. I looked over at her and asked if she was serious, she just shook her head yes. There was a park coming up before our turn to go towards the cabin. So I pulled into it and drove a ways into it. I parked off towards the end of the lot. I was so hard and excited at the same time I couldn't believe we were about to do this. I looked over at her and she crawled over the seat and got into the back. I looked out the windows and luckily there was no one around. I climbed in the back with her. She already had her shirt and bra off. I joined her in taking off clothing. Once we were naked she didn't waste any time and took my cock into her mouth. She was phonemanal at giving head. It has been a while since I had sex and with all the teasing I so ready to cum. I tried to hold back but about 5 minutes into her sucking my dick I blew my load in her mouth. She didn't stop sucking and made sure she got every drop before she swallowed it down. I was ready to fuck her when she said let's head back. I thought I had done something wrong but I got dressed. On the drive back I asked why we stopped. Ann said she wanted to fuck me but she wants to do it at the cabin, she said she wants the thrill of getting caught. I was surprised and thought that could be fun too. We got back to the cabin and my gf was down on the dock tanning. I helped bring the stuff inside and grabbed Annas ass as she walked by, she shot me a smile. She said she was going to get her swim suit on and I should do the same. I went and used the bathroom quick and then went into my room to change. When I walked in Ann had her top and thong on already and was waiting there. She told me to get changed and stood there waiting. As I was pulling off my shirt she pulled her top to the sides so her tits were out for me to look at. As I pulled down my pants my hardening cock sprang out. I grabbed my swim trunks and put them while Ann rubbed her nipples watching me. Once I got my trunks pulled up we started to walk towards the door and she grabbed my hand. She told me she wanted me inside her quick, just a couple pumps. She made a little pouty face and said please. I couldn't turn her down. She walked over to the window facing the dock and we could see my gf laying down on the dock still. Ann bent over against the window sill and pulled her thong to the side. She told me to stick it in her, that she was so wet and ready for me. I pulled out my hard cock and ran it up and down her opening before pushing inside. She was so wet and tight, much tighter than her sister. It felt so good to be in her pussy after waiting for what seemed like forever. She told me go slow and deep and only a couple times. I did as she asked and fucked her from behind slow and deep. Each time I pulled out she would gasp and then when I pushed back in she would moan softly. We only did this for about a minute when she said let's go swim instead. I pulled out and we adjusted ourselves. Ann went down first while I waited for my boner to calm down. I walked down to the lake and seen my gf was on her stomach now. Ann was out in the water with her arms up on the dock talking to her sister. She motioned for me to join her. I swam out and put my arms on the dock beside her. I was taller than her so I could stand without having to lean on the dock. My gf had her head facing away from us as they talked. I reached down in the water and pulled Ann's thong to the side. Ann shot me a sexy smile. I started to rub her pussy and clit with my hand while they talked. She kept looking over at me with a very please look and like she wanted to moan but couldn't. She was having a tough time concentrating on talking so I started to pull my hand away. Ann put her hand down in the water and pushed my hand back. She was shaking a bit and I figured she was close. I kept rubbing her pussy as my gf was talking Ann moved her head over to my shoulder and bit down on it as she started to shake. She was breathing slow and trying not to make much noise. She was able to cum so quiet I was impressed. She lifted her mouth from my shoulder and she had left a pretty big bite impression. Her eyes got big with a smile. I swam out into the water while the girls kept talking. I was trying to get rid of my boner again and hopefully that bite would go away a little. It was closer to supper time now so I walked up out the water and hurried inside to put a shirt on so my gf wouldn't see the bite mark. I grabbed some burgers and got the grill going for us. The girls mom came back from her hike that went longer than expected. She helped set the table outside while the girls were down by the lake. After the food was done the girls came up to eat with us. Supper was very normal and nothing happened during. We were discussing what to do for the night. We all decided to have some drinks and sit around the fire. My gf sat next to me and Ann was by their mom. We sat around and talked and drank till about 10. My gf was absolutely smashed again. She was all cuddly with me and had her hand on my leg. My gf said she was ready for bed and asked me to help her inside. I helped her into the cabin and she said she needed to use the bathroom quick. I waited by the door and once she was done helped her bed. Once I got her laid down she started to pull at my belt. She had this look on her face that I hadn't seen in a while and knew she was super horny. I wasn't about to pass up the opportunity. I was just starting to pull down my pants when I remembered I had that bite on my shoulder. So I walked over and turned off the lights. I closed the door a little and took my clothes off on the way back to the bed. I could hear her taking off her clothes when I got back. I climbed up on the bed between her legs and she told me to fuck her. I lined up with her pussy and pressed inside of her. She was moaning quite loud and telling me to slam her. I cupped her ass and slammed her hard. She was swearing and saying harder over and over again. I put my hand up to her head and pulled it towards my shoulder. She instinctly bit down pretty hard. I kept slamming her as she bit me. I seen the light in the hallway turn off and figured the others were going to bed. I kept slamming away at my gf. I looked over at the door and seen it looked more open than before. I looked back to my gf and she was still biting my shoulder. I felt her hands on my ass pulling into her deeper and deeper. I then felt a hand on the back on my head. I turned to see Ann was standing next to the bed. She put her finger to my lips. She stood and watched me fuck her sister for a bit before I seen her start to play with herself. I was so turned on I was really slamming my gf now. She said she was going to cum. I felt her tense up and her pussy clench down on me. She let out a loud moan as she came hard. I was still pounding her through her orgasm and when she was done told me to slow down that she was sensitive. I did long slow strokes in and out of her. She eventually told me to stop it was too sensitive. I pulled out and laid next to her. She had done this a couple times before where I could tell she just wanted to get off and then was uninterested. I laid next to her as she got under the covers and rolled away from me. I asked if she would be ready in a few to go some more and she said no she wanted to sleep. I looked to my side to see Ann walking out the door I thought I seen her motion for me to follow her. I put on my boxers and my shirt and left the room closing the door. I saw their mom's door was closed as was Ann's. I went out in the living room area and she was sitting on the couch playing with herself. She told me to come to her. I went over and didn't even ask what she wanted I just got between her legs and started to lick her clit. She grabbed my hair and pulled my face harder into her pussy. I tounge fucked her hole and sucked on her clit. She was moaning fairly quiet but still loud enough for someone to hear. I rubbed some of her juices on my finger and started to rub her asshole as I licked her. She just about lost it and started to fuck my face and said she was going to cum. She was breathing hard and moaning softly as I felt her pussy and asshole clenching while she came. When she was done she laid there for a moment to catch her breath. Ann then sat up and had me pull down my boxers. She straddled me and sank down deep onto my hard cock. We kissed as she rode me and grinded with me inside of her. She felt amazing to be inside of. I was still pretty worked up from just fucking her sister. Ann told me she wanted to feel me cum inside of her so bad. I told her I was pretty close and wanted to fill her up. She stood up and turned around and sat back down on my cock. It was so fucking hot to watch her sexy ass go up and down. I loved the feeling of stretching out her pussy as she went down. I grabbed her hips and started to push her down harder with each movement. She was saying she could feel me getting harder and knew I was close. She told me to cum inside of her and fill her up, she was begging and whining for it. I started to cum as she continued to ride my cock. I felt like I came forever inside of her and then she sank down deep on me and just sat there for a minute. She said she loved the feeling of my cum in her. She slowly stood up and I could see a string of my cum from her pussy to my dick. She turned around and kissed me. She then walked away and I heard her go into her room. I ended up falling asleep on the couch in my boxers. I woke up in the morning to the sound of the shower going. I went and got some water to drink and then went to our bedroom. My gf was still asleep so I grabbed some underwear and a shirt. I went back out and nocited Ann's door was open and the bathroom door was slightly open as well. I peaked in and could make out it was Ann in the shower. I snuck into the bathroom and closed and locked the door. I stripped off my boxers and went and opened the shower door. Ann turned and smiled at me. She said I was hoping you were going to join me. I hoped in the shower with her and we made out some. Ann stroked my stiffening cock while we kissed. Ann said she had so much fun last night and it sucked that we were all leaving today, I agreed with her. Ann got down in front of me and sucked on my cock for a little bit before she leaned against the shower and bent over. I spit on my cock and rubbed it up and down her pussy before pushing in. She moaned a little louder than last night because the shower muffled it. She braced herself against the wall as I hammered her hard and deep. She then stood up and turned around. We kissed some more and got cleaned up. We got dried off and Ann hopped up on the counter with her legs spread apart. She told me to come fuck her quick. I got between her legs and pressed back into her. I cupped her ass as I fucked her tight pussy. She leaned back against the mirror and told me she loved my dick. Ann reached down and played with her clit while I fucked her pussy. A few moments later she started to cum. I felt her warm juices run down my leg as she orgasmed. She apologized and said sometimes she squirts a little. I said I didn't mind one bit. I leaned forward and kissed her as I fucked her slow and deep. I could feel my balls tightening and knew I was close. I picked Ann up. She wrapped her arms around my neck and I grabbed her legs so I could put her against the wall and pound her. I came super hard inside of her and it felt so amazing. I set her back on the counter. She got off the counter and leaned over and took me in her mouth to clean me up. We kissed some more then she snuck out of the bathroom while I showered. After that everyone else was up and we all packed. We all said our goodbyes and Ann told me how great it was to meet me finally. I gave Ann a hug and even snuck in a ass grab. We all then left.