A metaphor that identifies the exact moment a TV show has reached its creative peak. Or to put it bluntly, it’s the beginning of the end of a once great show. The moment in which it becomes clear the writers are out of good ideas and the show has begun its decent downhill. It’s usually some ridiculous stunt, story line, major character change, or huge fundamental shift in the premise of the show that is viewed as nothing more than a desperate attempt to raise viewership and declining ratings. The phrase refers to an episode of the popular 1970’s sitcom Happy Days, in which one of the main characters is water skiing (while wearing his trademark leather motorcycle jacket mind you), and literally jumps over a shark.
As far as I’m concerned, America’s Next Top Model jumped the shark when Tyra chose that air-headed idiot Nicole as the winner, instead the much more talented and deserving Nik.