I mess with a teacher i had last year. My friends and i walk up to his room after lunch period every day, while he's teaching a class and start yelling "Where's our money, Chrissy boy, the boss is gettin' angry"
Just last week, in front of his students, he grabbed me by the collar of my sweatshirt and shook me. The class looked at him in fright, and i started laughing. Then we shrugged it off as a joke, which it was, but he could've gotten in trouble.