Funny bone

Bumping one’s elbow is known as hitting one’s funny bone because of the peculiar, tingling sensation that sometimes occurs. This sensation is not caused by the bone itself. It is in fact the ulnar nerve, which runs down the arm to the fingertips. There are two theories about the origin of the name. One is based on the funny, as in peculiar, sensation caused by striking the nerve. The other is that it is a funny or humorous bone, a pun on humerus, the name of the upper arm bone, which ends at the elbow. Whichever version is true, the expression funny bone is thought to have made its first appearance in the language during the early 19th century, even though people must have been hitting their funny bones for quite some time before this.