"Jumping the shark" is attempting to draw attention to or create publicity for something that is perceived as not warranting the attention, especially something that is believed to be past its peak in quality or relevance. The idiom "jumping the shark" is pejorative, most commonly used in reference to gimmicks for promoting entertainment outlets, such as a television series, that are declining in popularity.
Originally the phrase was used to describe an episode of a television comedy with a gimmick or unlikely occurrence desperately attempting to keep viewers' interest. Moments labelled as "jumping the shark" are considered indications that writers have exhausted their focus; that the show has strayed irretrievably from an older and better formula; or that the series as a whole is declining in quality.
Popularized by radio personality Jon Hein in the 1990s and early 2000s, the phrase derives from a scene in a fifth-season episode of the sitcom Happy Days in which the character Fonzie jumps over a shark while on water-skis. This was deemed a ratings ploy, for it was outside of the original thrust of the sitcom.
The usage of "jump the shark" has subsequently broadened beyond television, indicating the moment when a brand, design, franchise, or creative effort's evolution declines, or when it changes notably in style into something unwelcome.
The phrase jump the shark is based on a scene in the fifth season premiere episode of the American TV series Happy Days titled "Hollywood: Part 3," written by Fred Fox, Jr., which aired on September 20, 1977. In the episode, the central characters visit Los Angeles, where a water-skiing Fonzie (Henry Winkler) answers a challenge to his bravery by wearing swim trunks and his trademark leather jacket, and jumping over a confined shark. The stunt was created as a way to showcase Winkler's real-life water ski skills. However, the scene also was criticized as betraying Fonzie's character development, since in an earlier landmark episode, Fonzie jumped his motorcycle over fourteen barrels in a televised stunt; the stunt left him seriously injured, and he confessed that he was stupid to have taken such a dangerous risk just to prove his courage.