What are some good pranks to pull on your teachers?

What are some good pranks to pull on your teachers?
Theres an endless number, but they have to fall under 1 criterea sheet.
1.The teacher cant know who it is
2. It would work best on a stupid mean teacher (mean teachers are easy to find, stupid ones, not so much)
3. Doing it with your friends is optional. when doing it by yourself its easier to get away with, its easier to cover your tracks, but requires much more work.
4. it has to sting. something that they really hate. if theyre afraid of snakes, have a snake be a part the prank.
Maybe doing something with their chair, making it wobble too much so they fall.
If they read the newspaper, maybe find a way to put her name in the obitchuaries, and having the entire class be suprised she showed up to school.
(im only 13 so i have a ways to go, but this is what ive come up with so far. hope it helps)