crazy bone

[sumon9999]

a point on the elbow where the ulnar nerve passes near the surface; a sharp tingling sensation results when the nerve is knocked against the bone

[Gregory]

The term crazy bone is a colloquial term used to refer to a spot on the elbow, specifically the part where the ulnar nerve passes over the elbows end of the humerus (large bone in the upper arm). When the crazy bone is hit, it can cause a shock-like or tingling sensation. The medical term for hitting your crazy bone is ulnar nerve entrapment.