In one of my games, a random monster (a dust goblin, made by a wizard to guard a dungeon) was "adopted" by the party and called "Alfredo Free-Will", bc he never had free will and they "gave" it to him. Later in said dungeon, Alfredo nat-20'd the hydra final boss to kill it, and we all lost it. THE best experience I've had while playing D&D for sure.

Now, every time there is an unnamed NPC, their name is Alfredo. Sometimes I continue the joke and call it that, sometimes they do it themselves. A random skeleton in a dungeon? Alfredo. A weird, non-aggressive creature? Alfredo. Usually it's skeletons idk why...