What does butt of a joke mean?

"Butt of a joke" is an idiom that refers to the person or thing that is the target of a joke or is being made fun of. It usually implies a humorous or teasing nature, and the person or thing being referred to may not necessarily be present or aware of the joke. Another common phrase with a similar meaning is the "punchline" of a joke, which is the final part or twist that generates the humor.