When I was ten, I found a post that said that if you wear your underwear inside out, then everyone in the universe is wearing it but you. So, I did that for a full fucking year. Also, when I was in first grade, I took a piss on my school's football field when I was sure no one was looking during recess. Somehow, someone saw me and I had to apologize to all the classes that were outside for recess at the time for, y'know, pissing on a football field in broad fuckin' daylight.
Another funny story from my first grade year (Yes, I constantly got in trouble for stupid shit when I was six): one time, I got in trouble for being out of my desk during a test, so I fucking sprinted out of the room and ran around the school. Eventually, I went down a small hall and hid in the corner. A teacher, who was looking for me, walked by and saw me. I tried running past her, only for the fucking principal to grab my arm with a grip that was strong as fuck. Even after that incident, I did that a bunch of other times during the year, only to stop halfway through after deciding that I had enough of getting my ass whooped by my parents.