wall punching
A way of demonstrating how hard and/or stupid you are. At ours, it started off quite mildly but soon escalated t o the stage where the wall was being thumped so hard that shards of brick were falling off, and kids would come in to lessons with blood pouring from their knuckles. This was largely tolerated by the teachers and went on for some while until some kids hit on the idea of using their heads instead of their fists.
written by Ke*log , approved by Log

Also consider Locker Nutting, (headbutting a locker to non-English readers).
Quite painless if you hit the middle of the door, and you look pretty hard to boot. Rendered all the funnier when Paul Murphy asked the whole class to watch him do it then nutted the frame between lockers, making him cry like a gay baby.
written by Le* Ro*, approved by Log

Note to amateur locker-nutters: If the locker door falls off after repeated nuttings, don't feel compelled to throw it out of a second floor window, narrowly missing the caretaker's head. Maustin did this and is probably still in detention aged 26.
written by Jo*Breez*, approved by Conor