Only one I can think of is in Auto Service class a couple years ago in high school.
We were giving presentations to the next year's Freshmen and we had this distributor simulator that you could alter the gap of the "spark plugs" (really just grounded, adjustable bolts), and show different kinds of electrical problems having to do with the ignition system of a 6 cylinder car. Well, being the enterprising young men we were, and knowing enough about electricity to be dangerous, we had some fun with some jumper wires.
That day, we wired up chairs, car parts, tables, even a tranny jack to the "distributor". When someone would touch the offendin part, we would crank the throttle on the electric motor (which would put the RPM's up over 10,000) all the way and the poor bastard ouching the part would get zapped about 20 or 30 times before we had the common sense to let go or get off of the electrified part.
Hell, we even did it to the teacher. He got a kick out of that one
WIZZO
EDIT: Man, it was fun at the time, but it sounds boring in relation to the rest of these.