There are office pranks and then there are office pranks. This ceiling-mounted, ping-pong-ball-firing robot is distinctly in the latter category.

Built by someone from the CKBot group at UPenn's Modlab, this terrifying little device hides in the ceiling above a cubicle. When activated, it pops up a ceiling tile and unleashes a hot fury of ping pong balls down on the unsuspecting victim. It is, in a word, amazing. [Modlab via BotJunkie]