Dirty Jokes on 'Family Guy' (VIDEO)

What is the source of all dirty jokes? Yes, we all love them, but where do they come from? The search for the source of all bawdy jokes is the quest on 'Family Guy' (Sun., 9PM ET on Fox).

[Spoiler alert.]

Peter Griffin tracks down all nasty jokes to their origin. And their source might be a little more unexpected than you would think. It turns out that all dirty jokes are created on an island that is filled with smart people whose job is it is to come up with the zingers. One of the people on the island? It's Mr. Stephen Hawking himself.