Help her up and take her to the nurse.
Laugh with everybody else.
Just sit quietly untill everybody stops laughing.
Stand up for her/him.
Laugh with the person who is making fun of her/him.
Take your friends hand and walk away.
Tell her a lie that you have to study for a test the next day.
Say yes and lie to the girl and say that she is your best friend, then make fun of her at the party.
Use another boy/girl to make your ex boyfriend/girlfriend jealouse.
Go home and cry.
Take your anger out on writing an angry letter then tareing it up, and forget about him/her.