I remember one time when I was a kid and had read something mentioning spark gap transmitters. I of course found a bit of wire (tie wire because that's what came to hand, not anything insulated) and a radio and was playing around with a 9v battery making little sparks by shorting it with the wire and hearing the radio crackle in response. What I then thought was that if the little battery was making a noticeable effect then a bigger battery would obviously be better.

I got one of the drill batteries and shorted that out with my bit of wire to make a better spark and proceeded to discover that resistive heating is a thing and thin tie wire connected even briefly to a high discharge battery will get very hot very quickly. I ended up with a nice blister line across my fingers and a scar for a few years showing the position I'd been holding the wire...