The beginning of the end. Something is said to have "jumped the shark" when it has reached its peak and begun a downhill slide to mediocrity or oblivion. It's said to have been coined by Jon Hein, who has a web site, jumptheshark.com, and now a book detailing examples, especially as applied to TV shows. It supposedly refers to an episode of the TV show "Happy Days" in which Fonzie jumps over a shark on water skis, which Hein believes was the point at which the series had lost its touch and was beginning to grasp at straws.

After some significant event, everything from then on is terrible.