tl;dr - I wrote "sevral curse words" on a bathroom stall, (the actual ones like fuck; not the parent censored ones), and flooded a bathroom. They figured out it was me after having everyone in the school write something that began with "several students" and yours truly was the only one to write several as "sevral".
Longer Version - I had an IEP, (Individualized Educational Plan), when I was in public school. As I got older, I didn't really need it, but in elementary school, I absolutely needed it. It was mostly because I had problems focusing on stuff, and the fact I couldn't pronounce "th" or "s" sounds correctly. My school however, didn't really know what the fuck to do with me, and kinda didn't try to help me. Probably because I was Literally Satan Incarnate™ back then. I spent most of the day in the office because I was always in trouble for varying reasons. It was typically because I wasn't listening to the teachers, or I was fighting with other students, or I wasn't doing my work, or I was Literally Satan Incarnate™. You get the point.
It also didn't help that I was heavily bullied by my peers, to the point they would purposefully change the rules of games around until I decided to quit and sulk in a corner. The teachers also knew about it, but they didn't really bother with trying to solve it; I think because like I've said before, I was Literally Satan Incarnate™ back then. It did kinda lead to me figuring out that if I got into trouble and got ISS, (In School Suspension), they couldn't bully me, and that was one of the reasons why I spent so much time in there. But anyways, you get the general idea of how my elementary school was.
I hated it. The people hated me. I spent literally most of the time in there in the principals office, (to which my mom supposedly was never informed of), and I finished my work relatively quickly. So, I would just sit in there staring at a wall, thinking. Now, I don't remember where exactly I learned the curse words from, (much less where I got the sharpie from—I think I stole it from the principal's office?), but one day after gym, I decided I would go into the bathrooms directly across from the gymnasium with it, and write "sevral curse words" on the stall. Like I said in the tl;dr version, they weren't the parent versions—I literally wrote "Fuck" and other words like it on the stall.
The other thing I did that got me expelled was that I flooded a bathroom. Some of the classrooms were attached to another classroom by a small hallway with cubbies and a bathroom, and I learned if you were careful enough, you could lock and close the bathroom door without it unlocking. I also learned that if you were to take paper towels and place them on the drain, and turn on the sink, it would flood. From what I remember, it wasn't until a few hours later when one of the janitors was going through did they finally notice the bathroom was flooded.
The way how they caught me was extremely moronic too, in retrospect. They had everyone in the school, (at least, I think it was everyone), write a paragraph down that began with "several students" and yours truly was the only one who wrote it as "sevral". I do remember thinking in that very moment they had us write it down that it was to try to figure out who did it, but even with that, I still wrote it the same exact way. I think I over-thought the problem and ended up writing it how I wrote it on the stall because they wouldn't suspect it was me or something? I don't really remember.
There was also the fact that apparently a teacher saw me do it/leave the stall with a sharpie; however, if that was the case, I don't get why they would've had people write down that paragraph. And I also did hear later that I originally wasn't suspected of doing it, but when I was the only one who wrote several the same way, it was kinda obvious. I have no idea if either of those things are true however.