To “jump the shark” or “jumping the shark” has come to mean the moment in time when a once successful venture or business starts to decline. In contrast to other idioms, this one came about quite recently, being coined only in 1985.

In the 1970s and 1980s, a show titled Happy Days ran for 10 years. As the show progressed, one of the characters Arthur Herbert Fonzarelli, also known as The Fonz or Fonzie, proved to be a favorite with viewers, and more story lines were written revolving around him.

Fonzie was a high school dropout at the start of the series, and rode custom Harley-Davidson models. He was abandoned from young by his father and he had previously belonged to two different gangs. Despite his rough past, he had a high moral code, always sticking up for weaker parties and treating others with respect. By the end of the show, he had transformed from a rebel to a family man, adopting a young orphan boy named Danny to raise as his own, secretly attending night school to earn his high school diploma and going on to become a full-fledged teacher at the school.

During the show’s 5th season, an episode was aired in which Fonzie attempted to overcome his fear of sharks by performing a water ski jump over a shark. This episode aired on September 20, 1977, was later seen as the point in time where Happy Days had already reached it’s peak in quality and popularity and would go downhill from that moment onwards.

While the actual event that “jump the shark” referred to happened in 1977, it was only in 1985 that the term was coined by Sean J. Connoll, the roommate of radio personality and webmaster, Jon Hein. Jon Hein would go on to create the website, jumptheshark.com.

During this time, “jump the shark” had a different meaning. The phrase referred to the point in a televison series where the plot started to spin off into absurd story lines, having run out of ideas.

It is unclear exactly when the phrase adopted it’s current meaning.

One might also be interested to note that while the “jumping the shark” episode seen as the beginning of it’s decline aired in 1977, Happy Days still remained a successful sitcom for it’s entire run, although it never returned to the number 1 spot which it reached from 1976 to 1977.