If you thought the Annoy-a-tron was the ultimate in fiendish office prank technology, you'll love the evil new Phantom Keystroker V2. Rather than just merely annoying your coworkers with random hidden beeps throughout the day, you can now drive them absolutely insane with a small device that looks like a harmless USB thumb drive.
Simply plug the Phantom Keystroker V2 into any USB port on someone's computer (preferably in the back) and just walk way. Once installed it emulates a keyboard and mouse to make random mouse movements, toggle the caps-lock on and off and type out odd garbage text and phrases. There are setting switches that allow you choose it to do one thing or everything and an adjustment dial to set the duration between events.
The hardest part with this prank is trying not to laugh when the anger, frustration and screaming begins. The caps lock toggling on and off alone would be so irritating. Let us know in the Comments if you know of any more fun office pranks or devious gadgets.