There is a nerve that runs along the outside of the arm called the Ulnar Nerve. It is also called the "funny bone". The funny bone was given it's name for two reasons:
1. The ulnar nerve runs along the humerus bone in the arm (the bone from the shoulder down to the elbow) and humerus is a homophone for the word "humorous".
2. When the ulnar nerve is bumped, it gives the person a strange, funny, tingling feeling. Hence, a humorous feeling, from the "funny bone".
For more detailed information on the ulnar nerve, check out Wikipedia: http://en.wikipedia.org/wiki/Ulnar_nerve
