When your boyfriend has cheated on you, you get your friend to seduce and sleep with them for revenge. It doesn't logically work, but your friend gets to feel better about themselves and, if said friend is homosexual, your ex-boyfriend starts to feel very confused about himself and therefore you feel much better.
Person 1: I know he cheated on you, but he is really cute. If you want i can have revenge sex with him for you.
Person 2: ????