Hah, back when we were kids, we discovered that the strike anywhere matches would just fit in the barrels of our pump pellet guns, and when fired at a hard surface from a short distance, would snap like a cap and ignite. This led to the discovery that match heads could be used as a propellant, and could detonate inside a cavity when impacted. Eventually, we invented our own form of a mortar by drilling out the end of 5/8" rebar and placing a set number of match heads inside the cavity and inserting a bolt that would smash the match heads when the rebar was dropped onto a hard concrete surface, namely our driveway. We used a 5' long piece of two inch galvanized pipe as the mortar tube, and created a few rebar rounds and proceeded to launch our deadly little projectiles into the adjacent semi wooded area next to our house. The detonation was just soft enough that no one in the neighborhood detected it, and we usually found most of the rebar that we fired.

One day a neighbor kid suggested we make a bigger version and use more match heads and see what happens. So throwing good sense completely out the window, we got a longer piece of rebar, drilled the hole much deeper in the end, and packed a whole lot of match heads into it. When that rebar hit the concrete, it went off with a loud whack, and the rebar, which we could normally track as it left the tube, left our location for parts unknown, and none of us having a clue where. That wasn't the worst of it, for the bolt that was in the end of the rebar was now stuck deeply into the driveway, and the concrete had a spiderweb pattern of cracks radiating away from the impact point.

Needless to say, when dad got home, we got inquisited (dad always seemed to know that such damage was usually the result of our misbehaving). We had to come clean and got hided good for it, and sent to the wood pile for a couple weeks.

Then there was the time we tried to make little rockets out of match heads and tin foil, and ended up starting a mini forest fire behind our house. We lost a lotta hide back then...