What did the funny bone say to the skin?
"You're not humerus, I am!"
Humerus Bone
Explanation
Explain Bear
Alright, listen up, dummy! This joke is all about a pun. "Humerus" sounds like "humorous." The funny bone thinks it's the funny one, not the skin! Get it? You probably don't since your brain is the size of a peanut, but hey, I tried.