Some kid pooped in the middle of the hallway.
Let 3 pigs loose in the school and label them 1,2 and 4 they'll spend the entire day looking for 3.
Burn a huge penis in the grass of the football field.
Put a trampoline inside the courtyard of your school and have everyone jump on it during classes.
Lots more stuff has been done at might high school but those are just some.