http://www.edn.com/blog/Anablog/40759-Pranking_bosses_friends_and_competitors_.php
Here is one of my favorite segments (it involved a 'scope and a soldering iron):
You should beware of prank escalation. Len Sherman, application engineer at Maxim recalls a prank exchange with Jim Williams when they were at MIT. As he loves to do, Williams had bought an old broken oscilloscope and worked on it all day, bringing it back to life and perfect operation. After Williams went home for the night, Sherman put a piece of toilet paper under Jim’s oscilloscope graticule. The paper was unnoticeable, but made the scope trace fuzzy. It looked like a focus problem. Jim went crazy the next day trying to fix this problem. He had the covers off and was measuring all the high voltage circuits. It took a few hours before he found the paper.
To retaliate, Williams took the hinge pins out of the lab door and tied a rope to the doorknob that he pulled back into the room, threw over a beam in the ceiling, and tied to 100 pounds of ballast. The next morning Sherman put the key in the lock and turned the knob. The entire door left it hinges and glided, upright, back into the lab about 10 feet. It then stopped and fell over. “It looked like something out of a Stephen King movie,” recalls Sherman.
Sherman then rigged up a water nozzle to a photo-switch triggered by the lab lights. He rigged a soldering iron with coil of solder around it used as a fuse, to time out the prank. Sherman didn’t want to flood the lab, just run the water nozzle for a minute or so. Williams got wet.