The show never revealed the joke. Sources suggest that it is too dirty to say on broadcast television.
Family Guy continues to entertain fans with its shocking humor, infamous cutaway gags and epic episodes. The show has racked up numerous awards, including an Emmy Award nomination for Outstanding Comedy (it's only the second animated series in television history to be honored with such a distinction).
You can watch Family Guy full episodes at Fox.
Just In! A YouTuber sings 'Happy' in awesome 'Family Guy voices.' YouTuber Mikey Bolts is feeling like he's in a room without a roof and singing Pharrell's get-up-and-dance anthem in the voices of different "Family Guy" characters. Check out the video at The Huffington Post.