Nail gun explosive rounds
Rather a long time ago, in a different house, with a well stocked (my dad is best described as a womble with procurement issues) shed, I discovered a strip of nail gun rounds.

They look not unlike what would be used in a starter pistol; about 1.5 cm long, 1 cm diameter, copper, with one pinched end and an ignition point on the other flat end.

I was mildly interested in the power of the newly discovered ordnance, and having progressed to this point in my life via cap guns and devil bangers, I would absolutely need to find out.

The next time I found myself with some freedom in the house, I stole away to the shed, and concocted a test firing sequence plan.
Using a drill I put an appropriately sized hole for the round in the wooden bench, placed said round in it, then located a thin screwdriver and a hammer. The screw driver was put on the ignition point and the hammer was used to give it a tap. Nothing happened, and after a few more taps, I settled on a whack.

The following bang deafened me for a good ten minutes, I also had powder burns on both hands, as well as wooden splinters in both palms, both forearms and a few in my face. In short, minor damage, thankfully.

I had to spend the next hour or so, hiding evidence in the shed and removing all of the splinters from my person, and luckily I was never discovered.

I recently confessed this to my dad while visiting, much to his amusement, maybe it's because I did it while we were both testing out some of the little explosive doofers (also procured) that are used in fields as crop scarer's.
(ShiftyBastard won the World Cup on World Soccer Champs 2010!, Fri 25 Jul 2008, 14:28, Reply)