My physics teacher in high school loved experiments and loved to get the kids to play with them. One of which was a board with some light bulbs and terminals mounted on it, all bare exposed metal. To which he handed us a couple cut-off lamp cords with the wires split and stripped, so we could hold the wires by the insulation and touch the leads to the terminals.
I have no idea what he was thinking when he turned this stuff over to a bunch of 17 year old kids with no concept of the dangers involved, but I managed to create quite a shower of sparks while putting the classroom in the dark. It's an experiment none in my class will forget, at least.
