This also counts as a scumbag-move.
Back in Year 8, I was doing my art assessment; we had to make wire sculptures. Because I'm not a pusillanimous individual, I went up to my teach and said "Yo, I want to make a dragon". He was like "K. How much wire you need?" I did a quick sketch to check, and then replied with "3 spools." After a spit-take, he said "Sure."
A couple weeks later I had some wire in my back; I was working on one of the wings, but I had some left-over wire which I had forgotten to throw out. It was the end of lunch, and two of my friends and I had arrived outside G7 early. Bored and really not wanting to do class (it was either English or Religion), I looked at the wire in my broken bag and handed it to my idiot friend.
"Bet you $5 you can't shove this inside the door lock."
He grabs the wire and turns around, and then takes out a hammer from woodwork out of his bag. He starts banging away, and not 10 seconds later, the entire length of wire was gone. I couldn't even see it inside the lock. We tested the door handle, and it seemed to be fine; it was locked when we forgeted it, so there was no way to be sure without a key.
Eventually the class and the teacher arrive, and the teacher goes to open the lock. She has a face of frustration, and eventually quits. She silently walks away, and comes back with the Principal and the Groundskeeper. After about 10 more minutes of fiddling and trying to keep our laughing to ourselves, the Principal turns to us and tells us "You've all got an early mark. Go home."
I come back the next day; every single door in G-Block is replaced to the cost of $10,000+. Apparently, they tried another door, and for some incredible reason it didn't work either, and so they assumed all the doors were broken.