Way back in 9th grade, I had this foreign teacher who had little to no authority over the class. He had a super heavy accent that took weeks to finally get used to, so half the time we just milked it, acting like we couldn't understand him telling us "DON'T DO THAT" or "STOP THAT NOW."
I don't even remember the name of the class, but it was basically a study hall where you did your homework. But no one did that. We would just write BS in our study logs and show it to him, and he believed us. For the entire period, every single day, of that entire semester, we would all talk, have book fights (text books and dictionaries mind you!), eat, and throw things at the teacher. A friend and I constructed this sling shot out of paper and a rubber band and used it to fling paper balls at the teacher. I would practically fall out of my chair from laughing so hard when he looked around confused.
Halfway through the semester, he started giving us detention for misbehaving. Since we were the last period of the day, he would keep us after school (half of us would just walk out on him though), and had a list of names and would add X's next to them for each time after that we did something wrong. Each X was another 5 minutes after class (oh my).
Well guess what we did? We had a competition everyday: Who can get the most X's. I'm proud to say that I usually won, or was second place (or tied).
It was the funnest class of my high school experience, and probably overall.
And I'll laugh really hard if someone from that class actually reads this or recognizes the class/teacher ...