Surely they'll have a break-away connector on the cable such that you can't just reel the drone in. Or, maybe an emergency cut-away. Given that the burritos are only going to weigh a few ounces, even a bit of one or two pound mono-filament Nylon fishing line would probably be adequate, and cheap to replace.
As for the clay pigeon shooting, hey, what's better than shooting something out of the sky that you can eat afterwards?
Hmm, "Drop a burrito"; isn't that something you do in the restroom? ;-)
I'm sure they could probably increase the cool factor by streamlining the drone. Rather than your typical quad-copter, use one that looks like a B-17, and bomb the students with the burrito. You could probably get thousands of "gamers" to be drone operators in a scenario like this. Hmm, might not work so well in certain countries, though.
Anon Y. Mus
P.S. I'll get my coat. It's the one with the instructions for operating the Norden bomb sight in the pocket.