A friend of mine did this he got a glass cup like the ones baby food come in and filled it with something i prolly cant say(il give you a clue its white and sticky)then he let it sit in the sun for a few days until it was liquid and he put it in a teachers coffee. The teacher siped a little then put and ugly face then stired it a little more and drank the whole thing. Hardest part was trying not to laugh when ever i saw that teacher again.
There was one class that had a hole in the roof were the air conditioning was and someone got a paper that said throw all your tests here, everyone would crumble up there tests and throw them up there until one day that part of the roof fell and he made that class pick it all up.
A teacher went to the bathroom and left her laptop it was the art room so there was gojo(that soap that takes paint and grease off) they filled her keyboard with it and closed the laptop and put it in her bag,it was the last class of the day so she didnt notice until it was to late