Man i finish high school like 10 years ago but here it goes
Well i got kick out of my science class for like a month because i set the garbage on fire, now then, everytime i was suppose to go to my science class i had to sit in front of my principal office. One time she walk away from her office i heated up her door knob with a zippo lighter for like 5 min, when she came back she burn herself!
At the end of the year we would always organize a water balloon contest, it wasn't school organize it was me and some guys organize :P we bought a shit load of water balloon and water gun , give water balloon to everybody we encounter and then start a school wide (1,500 student) water balloon/water gun fight. We use to bring wrench and open fire hydrant too.
Of course the classic , duct tape porno magazine pages in the toilet
Food fight on spaghetti day that was a classic, the principal came in and one guy threw an apple and made an head shot!! he was expelled lol
Oh yeah one time we protested againts the lack of activity for the student during the year and ended up blocking an highway that was cool too.
Hiding the teacher key into the ceilling was a pretty common thing too
i could go on like that for many many post , these are just the one from the top of my head....