Someone took the ID badge from one of the guys that I work with. He took it to a vending machine, the kind that has sliding see through doors and the items go around on a spool. He took out the sandwich and put his ID badge in before he let the door close. It cost him $1.50 to get his ID badge back out of the machine.
One of the more popular tricks at the office is to set up someone's computer to auto-correct words to something completely different. Like their bosses names to auto-correct to booger pants.
You can also set up your email to automatically add your electronic signature. You do not personally see it before you hit send. It just shows up at the bottom of your email as seen by whomever you sent it to. Guys have gotten into other peoples email and have changed that to read all kinds of things. You can only guess how creative some folks have gotten with that one.
I have been know to get into a guy's email a time or two so I can send the boss a piece of HIS mind, or to "volunteer" HIM for some extra work. Heck, when my boss found out about it, he gave me a positive employee review for being "good with computers". LOL
.,