I think that teD is going to be forced to stipulate as to the difference between a "joke" and other humor forms. what about the 'elephant jokes'(1), the 'grape jokes'(2), the 'what's the difference'(3) jokes, etc., etc....

(1) how do you keep an elephant from charging?
(2) what's big and purple and swims in the ocean?
(3) what's the difference between a duck?

(let's see... that would be about... $150, american)