A point on the elbow where the ulnar nerve runs close to the surface and produces a sharp tingling sensation when knocked against the bone. For example, Ouch! I just banged my funny bone. The expression is a pun on humerus (pronounced the same as humorous), the Latin name for the long bone of the arm.
[ Early 1800s
A sense of humor, as in That comedian really tickles my funny bone. This expression is derived from def. 1.