Why does the funny bone tingle when you hit it?

There's no "funny bone."

This saying refers to the ulnar nerve which runs from the neck behind the elbow and down to the hand. When you hit somewhere around "the elbow," you aren't hitting bone or muscle. Instead, you are irritating the ulnar nerve which causes temporary paresthesia or numbness and often a tingling, "crawling sensation" down into the fourth and fifth fingers from ulnar nerve irritation from trauma as with hitting the "funny bone" or sleeping with the "arm asleep position."