Sending insects up was a regular one. Trash too, of course. A few grapes made the trip. The best one happened when we got hold of some dry ice. We found out that if you put a chip of it in an old plastic film can that it would develop pressure inside and blow the lid off. ( Don't try this at home, you'll shoot your eye out) So, of course, we loaded one, waited a bit to build up pressure and sent it up the tube. 30 seconds later we hear a pop and a lot of cursing. And when they looked to see how we had sent an explosive up, they found an empty can with no residue. HEHE.