These little gadgets are perfect for really really annoying your house mates: flip one on and conceal it somewhere, and until it's dark it does nothing. When the lights are off the fun starts, as the box starts to emit either the distant sounds of dripping water or a barking dog. Of course, your victim will turn the lights on to hunt down the problem, and the box falls silent. Brilliant. We love them, in a very seven-year-old kid amused by whoopee cushion and fart-powder kinda way. Available for about $10 each. [Red Ferret]