I'm going to yell at my aunt and young cousin after he ripped my birthday banner.
Do you think that's an appropriate reaction?
Yes! It was their fault. I watched them do it.
He is just a young kid, and it's just a banner. You should try to be more mature about this and not cause a scene. If it really bothers you that much just calmly talk to your aunt about it.
Well I'm gonna do it anyway. They need to pay for their mistakes.
Yelling at them will not fix anything. Your cousin is young and young people do things like that sometimes. Instead of yelling at him, you can just explain to him why what he did upset you or talk to your aunt about it instead.