What is the most stupid thing you've ever seen in school?

At my old high-school we had a t-shirt printing portion of the Graphic Design. I was the floor manager of that part of class, I was teaching kids how to print and was called to another part of the classroom. When printing tshirts via screen-printing you have to put them under a high heat lamp then run them through a conveyor oven. I came out of the Dark room to find the kids I was just teaching playing fortnite on their phones as t-shirt caught fire and my dumb ass ran over, picked it up without protection and threw it outside.