I don’t have a good answer to the question of why teenagers feel obliged to carry knives, but my cousin does, and you can read all about it here.
Or, if you want to ask her in person about it, you can actually go here. There is wine after. I’m just saying. I hope it is good wine. And I hope it is safe to get home after the event. If in doubt, go in a gang with some others. It should be bare wicked, man. Safe.
jam and giraffes 
I hope it is good wine too! Because it will make me feel safer as I walk home, without a knife.