I had a few of them, including:
1.) Starting a lighting storm with a rocket filled with small copper wires and an explosive because I wanted to see if it could be done. I did not plan on it causing a hail storm with it too, as I was unprepared for that part of
the reaction. Ahh, the fun....
2.) Experimenting with poisons, including extracting and purifying, as a kid. That one generally creeped out my peers. It did give me a head start on my future career as a chemist. My squirt gun (reserved for bullies) contained poison ivy/oak extracts. At one time, I had a few vials of rattlesnake venom that I was saving for a special project to protect our home from robbers.
3.) Collecting fireworks every year when the 4th of July holiday ended. They would go on sale and I would buy them on the cheap. They got stored in a special deep chest freezer, away from moisture and air. I hardly ever shot them off, as I wanted to take them apart to study how they were made (pre-internet days). That one aggravated my parents more than a little bit. I stopped buying them when I learned how to make better ones than what are commercially available for sale.
4.) Frankensteining my toys to make new ones. My older sister would break my toys to get revenge for something that I would do to her. I would then spend hours putting the pieces together to make “cooler” toys than the ones that I started with. It pissed off my sister to no end, as she had made me happy instead of sad.
5.) Reading about The Special Theory of Relativity in class when I was quite young. At the time, my teacher was trying to get us interested in reading, so she asked us to find a topic that we wanted to learn about. I picked that one. She did not think that I would understand it at that age, as she did not understand it herself. Well, I proved her wrong after I read it. I gave her and the rest of the class a long lecture about it. I could not understand how everyone else had a hard time learning it, when it came to me so easily.