My cousin, whose one year younger then me came home for Christmas from college. I hadn't seen her for two years and she really looked good. She wore tight black pants and her ass looked so good. We drove home together from the family Christmas party and I invited her up to my apartment when she dropped me off. We watched a movie in my room since I had a roommate and she laid on her stomach on my bed. We started teasing each other and I told her she had a flat ass, which was the complete opposite of reality. She said I probably had a small dick. I told her that if she said that again, I'd put it in her mouth. She did and I did. At first she didn't open her mouth and I got pre cum on her lips. Then she opened and lightly bit my dick before she actually sucked on it for a bit. I was gonna cum when she stopped. I was so horny that I took her pants and panty off and got on top of her. She was still on her stomach laying flat and I tried to put it in her. It wouldn't go because of the position she was in and I pulled her up on all fours, jammed my dick in her, pumped about ten times and it started to feel too good. I pulled out, tried to stop it but ended up cumming quickly on her ass. She teased me after that for such a short performance. I was embarrassed and didn't get a chance to prove myself.