Seeing as the statute of limitations has run out on this one I'll fess up to an innocent but STUPID move a friend and I made sometime around ninth or tenth grade (14-15 years old).
We had some 'firecrackers' that a friend of his dad had made and decided to light one in the playground of our old Junior High School. We didn't want to get caught doing it so we planned on using one of his mom's cigs as a delay timer. Great, but how to secure it... Ah, there's an empty Coke bottle over there. Hmm... Where do we put it? I know, over there in the grating on the cafeteria window (which consisted of a plexiglass paned window covered by a large reinforced metal grate with a small opening in the bottom to push food trays through)...
I shove the M80 in the neck of the bottle, place the cigarette on the fuse, and push the bottle behind the grate, between it and the window. Then I light it and we walk away. By the time we left the playground and walked up the street we figured it wasn't going to go off. As we stood arguing over whether to retrieve our explosive, the thing went off. LOUDLY. Taking the window, the grate, and most of the window frame with it... Needless to say, we ran. Fast.
Of course we had to go by a little later once the cops, fire trucks, and all the local residents had come to inspect the damage... We were anonymous among all the other onlookers and never did get popped for it. We were so stupid on so many levels it amazes me sometimes we ever made it to 18. I mean, how could we know a glass bottle with a large explosive jammed in the neck would act as a grenade? How could we know that the term 'firecracker' can actually mean M80 or larger when home made by a crazy eyed Viet Nam vet with authority issues and a HOT young wife not much older than us? (Ok, that part I threw in just because she was SO hot.) Seriously though, I was a stupid kid, but I wasn't a destructive one and I certainly wasn't a purpose driven vandal. I felt really bad about that one. Not enough to confess, mind you, but bad just the same!
I swear, we were so lucky not to be near that thing when it went off. After that I swore off lighting off random explosives in city limits from then on (unless they were actually designated as fireworks, of course).
Ah, good times... I'm really liking this thread.
I don't know that I should share any more but still, this is fun...