Ah, lemme think of all of the shit I got up to in school. I got frustrated with a couple of bullies in middle school (teasing me because I have autism, even though I spent most of my time in the same classes as everyone else; that didn't stop them from calling me a "retard" and plenty of other names. Others in my group of people who had learning disabilities and spent time in a quiet classroom to get away from the asshole kids; I still remember them because they were my only friends in that school - Louis, Kevin, J.J., and Gabby were the ones I interacted with most.) and I screamed, "I'll fucking shoot you when I see you again!"...in front of a teacher. Cue one week of suspension.
In elementary, I called one kid my "archenemy" because I thought the word sounded cool. He wasn't even mean to me; he just ran off in tears, and I didn't know why at the time.
And in high school, I was suspended multiple times for insulting teachers (because I was so done with teachers turning blind eyes from my time in middle school). And...I feel ashamed to admit it, but I turned into a bully myself during my freshman and sophomore years at a private school for kids with similar disabilities to mine. It didn't make me feel any better; I only hated myself more.
I did a lot of stupid shit as an adult as well, but it's my actions as a teen - particularly online, where I did some really terrible things to a group of teenaged friends - that haunt me even to this day.