ummm I've done plenty of stupid things.
#1 The earliest one I can remember when I was about 11 I think and I got sucked into Runescape badly and one night it basically brainwashed me, I was such a stupid kid spending so much time on that game back then. I remember taking a leak in the kitchen bin and didn't realize it's wasn't the bathroom toilet until I finished.
I think another time I don't know how the hell it happened but it was after Runescape again: I walked into my parents bedroom and threw a big bag of chips onto their bed (that we used to keep all those smaller packets of chips in at a younger age). I then said something like "Here's your bars!" after spending about 8 hours straight smelting ore on that freakin game.
Something other than that: because fireworks are illegal here in Australia and it was really hard to make any contacts to buy some from people who profit from it so me and my friends used to screw around and improvise.
Something we did a few times was to collect roughly a dozen empty deodorant cans we didn't need and buy 1 or 2 full ones, even bug spray - anything compressed in a can. I remember being 14 sneaking out of my friend's house, walking down to the service station and actually filling up 3 litres of petrol in a freakin plastic milk bottle and walkin off after paying. It's funny everytime the guy working there wouldn't question 2 young teenagers with long hair paying for petrol at 4am in the morning! This is 20 or so minutes away from our city.
We both live near a creek and a storm water drain each, so we'd fit all the cans and about 2 scrunched newspapers into a large pipe and go crazy dousing it with the petrol before lighting it and running, pretty loud explosions. Once it was at my house in a similar drain and the thing was I had to douse it AND light it - that's a bad desicion, I had petrol on my hands. Although I used a whole newspaper to light it was a torch, the amount of petrol fumes exploded and my hair partially caught on fire which was funny as all fuck, oh man I think that was the last time I did that.
I was a bit of a pyromaniac at that age, made what I could but I won't post how on this forum haha. I remember making Molotov cocktails just to throw onto the road and watch em erupt with my friends, playing what I can't remember was called but basically a tennis ball soaked in deodorant and lit, then thrown around a backyard with friends until it went out. Very fun until I confused compressed propellant with flammable liquid and set my hands on fire at another friend's house when I was about 15.
I've pretty much grown out of that sort of stuff especially now that my dad works on the trade side of the military and I have no idea if they monitor my internet usage if it's anything that would compromise my dad's security clearance which took him months to get even though he's completely clean.
So I've moved onto other stupid physical acts, like when I stapled the skin of my nutsack during a scavenger hunt for bonus points :P