I was at a Halloween party last year. Everyone was required to wear something that covered their face. I had joined in a game of spin the bottle and then shifted to 7 minutes in heaven. I was picked and a girl in a tight angel costume was picked. We went into the closet and began to make out. I fingered her and she rubbed and strokes me some before our time was up. We ended up meeting later outside and talking she took off her mask it was my step sister. We hadn’t said a word in the closet so I hadn’t known. I took off my mask and she got really red in the face. We put our masks back on and started making our way through the crowd but instead of leaving she pulled me to the bathroom. She told me to leave on the mask. We ended up having sex on the counter and I came inside her. We never spoke of that night and haven’t hooked up since