When you're mad at somebody, when they walk by you yell out stupid insults that fit you.
Like so:
If you're a slut that lost her virginity with a guy you didn't know, call the person you're mad at "slut".
If you're a person who wears pants that deform your ass and have stupid greasy hair and dorky glasses, call the person "cheesy"
If you tell the most stupid lies about how you tried to kill yourself with an overdose and woke up in a hospital having your stomach pumped, or about how you kissed this or that person when you really didn't, then call the person you're mad with, "liar/fake"
Yeah, that shows how mature you are at the age of 16