Two incidents come to minnd.

The first, I was in 7th grade and there was a kid in my English class that was an asshole to everyone and liked to try and steal from me , but the teacher would never get on to him. (I guess the dislike the teacher had for my brother 6 years before passed on to me. ) One day the kid was reading his report at the podium but kept lowering his hand to the side and flicking off everyone. There was no way the teacher didn't see this and I was tired of his bullshit so I got up and punched the kid in the face. The teacher starts yelling at me so I yell back about how he doesn't do shit, told him to go fuck himself, then went to the office. Ended up getting suspended for a few days before Christmas break.

The second, was my Spanish teacher in 9th or 10th grade. I have bad eyesight so I had to work with teachers around the issue during school. This teacher refused to be helpful and after talking to her and higher ups about the issue it was clear nothing was going to be done. At that point, I decided to start resting through the class and take something different next semester since I couldn't see what she was doing.
Every so often she would get on to me for it and I would barely acknowledge her. One day in a loud voice but not quite a yell she tells me not to and follows it sometimes like " Don't you understand the words I'm saying" U replied with " I dont understand the majority of what you say" ( she had a really strong accent) and she kicked me out. The higher ups let me switch teachers after that but the new teacher was out of textbooks. I had to ask my former teacher if I could keep the book she assigned me and she said no. That annoyed