When I was 14-20 I would just find something I was sure that young ignorant to-be bully was self conscious about and poke that. I think I did it at a job I was later fired from for a completely different reason. A kid said "you sound funny" point and laugh style. I said "at least my teeth don't look as funny as yours" and because he had really bad teeth he shut right up. Parent was offended but the place was a greasy small-town fried food establishment and no one ever talked to me about it lol