[pennsiveguy]

Okay, who else had a home-made tennis ball cannon?

We used 4 or 5 tennis ball cans, with the bottoms cut out of the top 3 or 4 and duct-taped together end-to-end. Had a small vent hole in the bottom one. Drop a tennis ball down into it, shoot some Aqua-Net hairspray into the vent hole, and set it off with a lighter. Probably only went 100 yards or so, but it was big fun for us.