Jaws was the movie that gave us the word "blockbuster" in 1975. Of course, they made Jaws 2, without Steven Spielberg. Producers David Brown and Richard Zanuck thought making another sequel after that would be stretching things unless they came up with a different idea. How about a comedy? They approached National Lampoon, which had a hit in 1978 with Animal House. National Lampoon writers John Hughes and Tod Carroll started working on a script for Jaws 3, People 0.
The premise of the film was that a Jaws sequel was being filmed at a beach when an executive producer was eaten by a real shark. The shark continued attacking the cast and crew, while the movie executives fought amongst themselves. Oh yeah, and the shark was from outer space in at least one version of the script. The film was announced and the roles were cast, but Jaws 3, People 0 was never made. The reason it was canned varies depending on who you ask, but there could have been many reasons. Ultimately, there were two other Jaws sequels released (Jaws 3D and Jaws: The Revenge) that were not intentional comedies. Read the story of Jaws 3, People 0 at Mental Floss.