I was about 7 or 8, and I wanted to have my remote control plug into the wall, instead of needing a 9 volt battery.
So I cut off the plug that connects to the battery terminals, and cut off a cord from an old lamp that didn't work, and I spliced the two together.
When I plugged it in, nothing happened, and the remote didn't work. I figured the wires were not crimped tight enough, so I grabbed a pair of plies and crimped them tighter. The problem was, I didn't unplug the cord from the wall.
When I crimped the wires, I got one hell of a shock, and the surge melted the cord and the remote circuit board.
That was really a dumb thing to do.