What did your school do for muck up day? Ideas?

At my school its banned, so we just did small stuff like wrap the heads car with toilet paper, set out a class room on the field, stole every board marker in school, soaked people with cheap perfume, duck taped the annoying peoples bags to the top of a lamppost, then the annoying kid to the bottom of the post :P

I can't think of what else we did...