What does the phrase "jumping the shark" mean?

Question

What does the phrase "jumping the shark" mean?

Answer 1

It means something that's no longer as good as it used to be - usually like when your favorite TV show is no longer entertaining.

It comes from an episode of "Happy Days", when a character called Fonzie (The Fonz) performed a water-ski jump, over a tank with a shark in it.  Supposedly that's the point where the show's writers were out of ideas and resorted to a cheap stunt to keep interest in the show.

So if the show isn't any good after a certain event, that's when the show "jumped the shark".