we've set up some guidelines for pranks at our camp (i.e. among staff only, etc)

over the last couple years:
* a few admin staff had a series of pranks on the director:
first off, a few years back we were trying to decide what to name the director's cabin, and some staff came up with the Loony Bin - though our director didn't like it. so it's kind of a camp joke that that's the cabins name.
anywho, one summer we gave her car new liscense plates that said "luny car" or some such. the same summer we labeled everything in her office - loony chair, loony stapler, loony office, etc. etc.
the same director also is not very fond of the song "Stuball" (about the race horse). so we decorated the camp golf cart like a horse and named it Stuball.

another group of counselors decided to transplant one of the kitchen/unit helpers bed into the dining hall - the cot, sleeping bag, pillow, and all - including the mosquito netting and her alarm clock! it was right before dinner, and all the campers thought it was funny!

those are the ones that come to mind right now.