Jump the shark

[Britney]

a term to describe a moment when somethin that was once great has reached a point where it will now decline in quality and popularity.

Origin of this phrase comes from a Happy Days episode where the Fonz jumped a shark on waterskis. Thus was labeled the lowest point of the show.

[Britney]

The precise moment when you know a program, band, actor, politician, or other public figure has taken a turn for the worse, gone downhill, become irreversibly bad, is unredeemable, etc.; the moment you realize decay has set in.

[Tina]

Original meaning was the point when a television series shows it has run out of ideas and must resort to stunts to retain viewer interest. Derived from a scene in the last years of Happy Days when the Fonz waterskied over a shark. Includes actions such as it was all a dream episodes, live episodes, lead actors playing guest characters, and putting entire cast into a parody of some pop cultural event.

[Sonia]

Refers to the specific moment when a TV show goes downhill. From the Happy Days episode where Fonzie overcomes his fear of sharks by jumping over one while wearing water skis.

[Becky]

when something stops getting better and starts getting worse

[Jason Yan]

Hung around too long. Kept something going when it had obviously run its course or became useless.

[Luis Fok]

to reach the point where the poupularity of a show, movie, musician, or any other pop culture icon declines in popularity (refers to an episode of The 1960s TV show, Happy Days where Fonz jumps over a shark while water skiing, see also [jump the couch])