Too much to mention...
Let off a fire extinguisher and threw it down the middle of the staircase when I was in year 9, a year 11 got the blame and expelled!
Sold dodgy cigarettes to the chav kids for £1 each, sold dodgy ale my grandad brewed to other kids - the stuff was vile.
Threw those little plum berries at random people and started a trend of "berry wars", those things were lethal and I'm still amazed no one was seriously hurt.
my mum used to do tags for well known high street stores from home, she had massive bags of elastic bands, I flooded the school with them and again, elastic band wars ensued.
Told the deputy head to "f off" in a casual come back to him telling me to behave, I had to stand in his office all day, no sitting, no lunch and no talking - certainly taught me a lesson to think before speaking.
Stole petty cash from the first aid room - was stored in an old tin on a shelf, was just being noisy and I and a friend split it - that very same friend stole my bike, karma.
....inner city schools are rough, I was one of the good kids!