Jump the shark
Definition 1 of 1
Pro Tip 1/3Origin Story
Understand that 'jump the shark' comes from a TV show episode where a character did a ridiculous stunt signifying the show's decline. 
The phrase 'jump the shark' is from when Fonzie water-skied over a shark on 'Happy Days'.
Pro Tip 2/3Cultural Use
'Jump the shark' is often used in entertainment contexts, such as TV, movies, or books, to mark a quality downturn. 
Critics said the film series 'jumped the shark' with the fourth sequel.
Pro Tip 3/3Idiomatic Flexibility
The phrase can be modified to fit different forms, like 'jumping the shark' or 'has jumped the shark'. 
The ongoing TV show is jumping the shark this season.