My sister and me go clubbing together, and sometimes when she gets very drunk she grinds her ass into my dick on the dance floor. The last time she did it my dick got hard. I feel sick when I think about it. I know she felt my cock, but she just kept grinding. I must admit I was enjoying the moment, but now I feel sick. The only thing that keeps me sane is the fact that we were both drunk and high. I hope I don't start dreaming about her. She is older.