NPR's guide to the running gags from the show.
Various titles are spruced up with the prefix "Mister."
4 episodes feature this joke:
Mister Movie Producer
George Sr.: "I don't want to be Mister President."
Sources: Joke data compiled by Adam Cole / NPR. Episode metadata from The TVDB via a Creative Commons Attribution 3.0 United States (CC BY 3.0 US) license.