Trombum? Drumbone?

What should I call this thing? It's a tunable drum that works like a trombone.
Last night I had a bit of a party over at my house, and in the midst of it all, my friend Nick and I got to talking about Potato Guns, the US winning the space race, and other fun stuff. That's when the PVC pipe came out of the back room.
Now, a word about my parties. They are dry. That is to say there's no alcohol involved whatsoever. We're all crazy enough, though, so some really weird things get done, said, and, as you can see here, made.
The PVC pipe in question was sitting in my workshop, just the other side of the wall from the room in my basement that we were having the party in. Next came the tubing and the duct tape. By the time that Nick had left and it was down to just three of us, I had a funnel involved. I asked my friend Joe what he thought I could do with this, and he merely shrugged. Tape over the funnel provided a handy drumhead, and some duct tape on the slider pipe made for a slightly better seal.
I already had a fixed length pipe (see the first picture above) to shove in the end with a pretty good seal, and viola! The drumbone, trombum, trum, or whatever you'd call it, was born.
Hear it in action!