Let's face it, everyone has moments when they feel they have encountered or become evil DMs. Whether they nerf your character, get overly creative, or have a bit too much fun telling you what you cannot do, some of these mortifying experiences can turn into terrific (and hilarious) stories.

Here's one from my DMing experience:
As a bit of background, a male player requested to be a female cleric. I knew that he was immature but I allowed him and warned him to act his age...
1 Week Later
Me: I'm sorry. I warned you this would happen. A girdle of gender changing pops from mid air, clamps onto you, and disintegrates.
Cleric: What? Aren't you going to give me a warning?
Me: I already did.
Cleric: Wha?! Can't I at least make a fortitude save?
Me: Why not?
Cleric: Yes. Natural 20.
Me: Congratulations. You succeed... for half effect.
Cleric: Wait, I'm a hermaphrodite?
Me: Not quite, after the girdle removed your gender, you resisted its attempt to give you a new one. You are now completely genderless.