This is an idea for a plot that I could come up with while incredibly drunk in a bar.
Oh, wait, I already had a slightly similar idea some years ago. But better, I think.
It's a teenage comedy about a boy who's got a crush on this girl but she has a boyfriend who's a huge douche, and he doesn't know how to get her. Finally he decides to pretend to be a woman and seduce the boyfriend, and make sure the girl catches him cheating on her. Didn't think of what happens next, but I think the story should get even weirder from here.