Jump the Shark

An unusually precisely dated idiom. It refers to a real 1977 episode of the American sitcom Happy Days, in which the character Fonzie, on water skis, literally jumps over a shark. The stunt happened because actor Henry Winkler was a genuine water-skier and wanted to show it off, not because the writers were struggling for ideas at that point. The phrase itself was coined years later, in 1985, by radio personality Jon Hein and his college roommates, discussing exactly when TV shows start going downhill, and cemented into wider use once Hein launched the website JumpTheShark.com in 1997.