I think the dumbest thing I've ever done was when I was a kid. We lived In Berwick, not far from the east coast main line and the signalbox at Tweedmouth. I had the dog out along the old branch line walking towards the junction and signalbox. I decided to explore the overgrown area behind the signalbox, found a small metal disc, about 2" in diameter, ½" thick. I thought this must be one of the explosive things they use to warn trains. I took it home and, you're not gonna believe this, decided to see if I could make it go off with a hammer. I put it on the back step of the house and, dog standing beside me, proceeded to hit it with a hammer. On the third or fourth blow it went off, HOLY F...
I was stone deaf, the dog disappeared for for about 15 minutes. I have no idea how I wasn't injured. I ending up in the rail industry and you have to stand 30 yards away from detonators to avoid the possibility of flying fragments if they are exploded, I was kneeling right over it!