A German joke. Clue: "wer" means "who" in German and is conjugated.
One night a werewolf went to a schoolteacher's grave and woke him up.
"Conjugate me", he said.
"Der Werwolf", said the good man.
"Des Weswolfs, genitiv so"
"Dem Wemwolf, dativ, as it's called."
"Den Wenwolf, and that's all".
Poor werewolf! He had wife and children, though! He went away in a disastrous mood. Well, there are many wolves, but wer just exists in singular.