There are all sorts of horrendous medieval or high-tech punishments you can mete out on characters in a game.
But sometimes the best ones are the simplest, those that strike a chord with the players. Having a character drawn and quartered is kind of abstract, but having one be made to sit in the naughty chair with their nose to the wall is profoundly embarrassing and visceral.
Especially if you do it to a noble in the King's court.
Yoda: Dookû, you're coming with me!
GM: Dookû uses Force Drain lightning on you.
Yoda: I scrunch the lightning up into a ball and throw it away!
GM: With your bare hands?
GM: It's not easy to get rid of. It's feeding on your anger.
Yoda: I'm not angry.
Yoda: Just very, very disappointed in you, Dookû. Such a good Padawan of mine you were.
Count Dookû: Ah was?
Yoda: And now a sore loser you are. Agreed to the Arm-Wrestle, you did. A lesson you need to be taught.
Count Dookû: Very well... old mastair. Ah am ready!
Yoda: Good! Say one hundred times: Jedi don't break promises!