What is the best prank you ever pulled?

Don't know about pranks. I had a roommate in college and when he was away I used to sneak into his room and arrange a group of stuffed animals on his bed in highly suggestive sexual positions. He entered his room more than once to find his childhood companions in the middle of an orgy.

I can't recall why we had enough to make it worthwhile. I think it was because my folks had just gotten a new dog that was a puppy and loved plush toys (he still likes them) and so I cleared out any that I didn't want chewed on.

This happened at work a year ago, and I still laugh about it.

My co-workers wanted to do something funny for a secretary going on maternity leave, so they got lots of pink post-its (lady was having a girl) and while she was in a meeting, five ladies and I got all those post its, and covered her car. The ENTIRE THING! We were rushing, and got some attorneys into it too, and random people in the parking lot. She was surprised, and had to take off all those post-its. It took her awhile. :)

I've done something like that to a lady with aluminum foil on her entire desk, including the pens, computer, keyboard, from top to bottom. Not really mean stuff here, but it was funny...

Okay, so this is totally childish, but it's the one that stands out in my mind.

At summer camp once when I was 12, it was the first year that I bunked in the older girls' cabins (12-17). The older boys' cabin woke us up at 4:30 am every day by banging on the aluminum siding outside the cabin and yelling at us. So, for the last day, we got our counselor to go to the store and buy us lots of shaving cream and silly string and a really long roll of plastic wrap. That night, we went over to their cabin around 3 am and stole all their clothes off the line. It had been rainy earlier that day, so all their muddy shoes were outside too.

We threw their clothes up in the trees and ran their boxers up the flagpoles, and put all their shoes on the bathroom roof. We then completely wrapped their cabin in saran wrap, so that it covered the doors and windows and everything. Then at 4:30 when they came out to wake us up like usual, they attempted to run out the door and the first guy ran straight into the plastic wrap, falling backwards and knocking over all the other guys behind him. When they finally did make it out, we ambushed them with the shaving cream and silly string. The camp administrators supported us cause the guys had been so rude with the wake-up calls the whole time, so they made the guys climb up to get their clothes and shoes and clean up all the mess. :)