I’m watching a college baseball game and a hit ball struck the pitcher around the elbow. The announcers mentioned that it might have hit his “funny bone”. Checking it out, I was surprised how far back the expression goes. Online Etymology Dictionary has this:
Funny bone “elbow end of the humerus” (where the ulnar nerve passes relatively unprotected) is from 1826, so called for the tingling sensation when struck.
Collins Dictionary has this, which I’d bet is more correct than the weird feeling of being hit there or bumping the elbow into something:
Word origin of ‘funny bone’
from its reaction to impact, but prob. suggested also by its relation to the humerus (hence, “humorous”)
I would imagine everyone has experienced the feeling, and it sure doesn’t feel funny at the time. Yet, some do laugh in a painful way.