Jumping the shark: Happy Days
Jumping the shark is the moment when something that was once popular that no longer warrants the attention it previously received makes an attempt at publicity, which only serves to highlight its irrelevance. This is especially applicable to television series or other entertainment outlets.
Popularized by Jon Hein, a radio personality from the Howard Stern Show, in the 1990s and early 2000s, the phrase derives from a scene in a Season 5 episode of the 1970s sitcom Happy Days in which the character Fonzie jumps over a shark while on water-skis.This gimmick strayed absurdly outside the original storyline of the sitcom.