B.Y.O.S.S
A game rule that forces you to bring your own stat sheet or you’re going to be mocked, humiliated, and possibly turned into a goblin.
Player: 'I brought my stat sheet, but I also brought my baby sister. She’s playing too.'
GM: 'You didn’t bring your stat sheet. I’m making you wear a hat that says 'I’m a clueless idiot.'
Friend: 'I got turned into a goblin because I forgot my stat sheet. It was the worst.'