So this girl is annoying me...

[A Bad Clown]

This is good:

First off, at lunch start eating with your mouth open. Then later say many rude comments and call her fat. If she calls her boyfriend, say she's cheating on him with another woman. Unite with said boyfriend to stop her and tell her you're both gay. She will get mad and leave, and then tell the boyfriend you aren't really gay so he can stop rubbing your arm.