We've had threads on how D&D itself has a colonial mindset, but I think that undersells how fucked up and racist players can be. I want this thread to be about players who go out of their way to make characters that break the fourth wall and ruin friendships outside of the game.
I'll start: I had a player come to me with their character: "Gucci, the rapping goblin bard". The details were what you would expect. Like he literally put a picture of Gucci Mane in the chat. I told him that this was blackface and I wouldn't allow it. He had a tantrum about being called racist, and now we no longer speak (lol).
Damn, I'm lucky. The worst I got was a Kenku named cheese who got the party kicked out of almost every town they entered after stealing all their cheese. He would escape by being carried away by a swarm of bees.
He died in a tragic drinking competition mishap.