As for me, three stories in particular come to mind. I'll let you decide which of them was the stupidest.
1. I once took a shit inside the shower. I'll leave the full details of the event up to your imagination, but to make it short, it was a combination of having diarrhea and losing a game of Russian roulette. Let's just say... the results weren't pleasent.
2. I once kicked the school bus after getting out of it, just for fun. I don't quite know why I did it (I mean, I was just a stupid child), but out of all the days I could have done that on, I probably shouldn't have picked the one where that very, very angry, intimidating, androgynous woman was our driver, because as soon as she saw it, she immediately came running out with her face turned red from anger, and I guess among the hundreds of scratches that were already on the bass, she noticed the one that was, allegdly, caused by me. You gotta realise how ridiculous this claim was. I was just an elementary school boy. I didn't possibly have the power to cause an actual scratch in the bus, plus, I wasn't even kicking it with a lot of force. Not to mention that, as I said, there were literally hundreds of scratches on the boss alrady. Nevertheless, this stupid thing I did got me into quite a bit of trouble, and in the end, my parents ended up having to pay around 500€ in damages. Not necessarily a neck-breaking amount, but it sure didn't make them very happy.
3. My childhood friend once accidentally burned a CD with some porn on it for me. He didn't even know it was there. I just wanted a CD with emulators and ROMs, but his brother's friend (or someone like that) snuck a ton of porn into the emulation folder and made it hidden, so my friend burned it onto the CD for me without even knowing it. The thing about hidden folders is that they don't maintain their hidden status once burned to a CD (or at least, the folder in this case didn't), so on my own PC at home, I actually stumbled over the porn folder immediately. Well, anyways, the stupid thing that I did was that instead of getting rid of it as quickly as possible, I copied all of the files onto our PC somewhere and kept looking at them occasionally, and eventually, my brother found out via Irfan View's "recent files". This ended up not only getting myself, but also my friend in big, big trouble. You gotta know, I grew up in a srictly Christian household, so of course it did. I think I wasn't even in puberty yet. I don't remember everything that was there, but some of the things I do remember were hentai (Dragon Ball, Sailor Moon and possible some others) and some deep fakes of a German celebrity (of course at that time, I didn't even know what that was and just thought it was actually her). From what I understand, the things you consume as a child strongly influence what you feel attracted to as an adult. I don't know if that's true, but if it is, then this event probably contributed a large amount in shaping my sexuality today.
Feel free to visit my website/blog - it's updated rarely, but it looks pretty cool!