The Compton Gangbang
You meet a young lady at the bar. She tells you she has a boyfriend, but she ends up going home with you anyway for a one-night stand. When you take her to your place, tell your friends to wait outside your bedroom door. Just when she's about to get off, your friends barge in the room and plainly beat the shit out of her. That should teach her not to fuck around. (Ladies, feel free to perform a Compton Gangbang on guys too. I know you've got some fat girlfriends to help you out.