
That, my friends, is an air-powered pumpkin cannon. It is located at a farmstand very close to my school. The guy who owns it built this thing, probably because he was bored, haha. This thing was actually featured in a Popular Science magazine, in the "You Built What?!?" section. Unfortunately I don't remember which issue. I think it's really cool; all the more so because it's so close by. I've never actually seen it shoot before, but it apparently launches pumpkins like a mile. I would love to use it to hurl about 50 water balloons through the air...
Here's a close up. You can see the loading mechanism and the massive air tanks. It's pretty much nothing but a gigantic WBL.

There's a video as well. I believe I actually showed this to Scott and DX when I was in CT. This thing is like the ultimate redneck toy, haha.
Enjoy.