I worked at a convention center as a teenager, and when April 1st came along, I was smart enough to park my car in a neighboring parking lot. That day:
-The manager's car got shrink-wrapped to the light pole he parked next to.
-We picked up a co-worker's Ford Festiva, moved it around the corner of the building, taped a table skirt around it, and dumped a gallon bucket of mustard (taken from the concession stand) on his windshield. It stained the windshield.
-Sugar was poured in the pots of coffee, and mugs were superglued to the break room table.
-Forklift grease was spread on the seats of the forklifts.
