Someone who insults a girl after he has been rejected by her. A Deal Buster will usually do this so that the girl won't walk away with the satisfaction of bieng hit on. He also has no interest in talking to her again.
Deal Buster: Hey whats up it's me I was just calling to see if you wanted to hangout tonight.
Girl: Well....I would but I have to go to florida tommorow for two weeks..and when I come back i have to go to Ohio.
Deal Buster: It's alright your Fat anyways.
Girl: Oh my God! Your so immature!
Deal Buster: LOL