The Phantom Keystroker: Office pranks go hi-tech
While the Phantom Keystroker looks like a harmless circuit board it's actually the office prank equivalent of Chinese water torture. All you have to do is attach the device to any USB port on your victim's computer and before you can say Jack Robinson the Phantom Keystroker will be causing unprecedented havoc.
The device periodically makes random mouse movements and types out garbage text and phrases. You can also choose between either keyboard garbage typing, annoying mouse movements or both to increase the torture. ThinkGeek recommend that you don't set the Phantom Keystroker too frequently in order to extend your victim's agony.
Your unsuspecting co-worker will think his computer has been infected by a destructive virus and as he fumes with anger you can act concerned and offer to call tech support while secretly giving your self a pat on the back.