You're going to want to turn off your speakers for this one. Actually, just to be on the safe side, you may want to light them on fire, smash them with an axe and then pour hydrochloric acids over the spark-spitting shards. This video has terrible music. But the reward is worth it: a look at the Disintegrator, a rubber band mini-gun made out of wood that fires its payload at an incredible 40 rounds per second. Of course, loading it is an hour long affair, but that's a small price to pay for the pleasure of turning your office colleagues into a perforated column of meat jelly during an impromptu office rubber band fight.
The Disintegrator [YouTube]