A joke told which no one laughs at, it is so bad it doesnt even get a pity laugh, it makes you want to kill the guy who said it its that bad. So bad you lose all the respect you had for the guy. Its so bad that you become dumber having heard it.
Pat: Why did the elephant cross the road?
Pat: Because he was following the chicken
Scoop:...(confused look on his face)
Pat: Get it...cause the chicken crossed the road..be..fore..
Scoop: Thats what we call a Pat Joke