Definition: the point at which a television series has reached its peak, and begins to decline in quality, often resorting to last-ditch efforts (e.g., introducing a ridiculous situations or a bold, new characters) to boost ratings. More generally, the phrase is used to refer to the point at which something that is good goes bad or something that is popular becomes irrelevant.
Variation: to jump the shark, jumped the shark, jump the shark moments
Origin: The phrase was coined in 1985 by Sean Connolly who was a student at the University of Michigan in Ann Arbor. Connolly and his college pals were discussing when television shows had reached their peak and then began going downhill. Connolly recounted an episode of Happy Days from season five (original air date: September 20, 1977) when Fonzie, played by Henry Winkler, clad in swim trunks and his iconic leather jacket, strapped on jet skis and jumped over a shark in the ocean. Fonzie literally jumped the shark — and a colorful new phrase leaped into existence. However, it was Connolly’s roommate Jon Hein (then a member of the comedy troupe “Comedy Company” and now a radio personality) who popularized the phrase when he created the very popular website, JumptheShark.com, which listed more than 200 TV shows that had jumped the shark. Hein was also a popular guest on the Howard Stern Show where he discussed the shows that made the dreadful jump. Soon after, Hein authored two books on the subject. In his book, Hein, defines “jumping the shark” this way: “It’s that moment you know your favorite show has lost its magic, beginning the long, painful slide to the TV graveyard… The essence of “Jump the Shark” is this impassioned debate, and it’s not just limited to television. Music, sports, movies, politics… all of pop culture is subject to strapping on the skis.” According to Hein, there are a variety of ways that a television show can jump the shark: new characters, special guest stars, cast members leaving, replacing cast members, birth, puberty, graduation, marriage, death, singing, sex, relocating, or a vacation. But no matter how a show jumps the shark, once the blood is in the water — the show’s demise is imminent.
For further reading: Jump the Shark: When Good Things go Bad by Jon Hein, Plume (2003)