I can’t believe I’ve lived almost 40 years and before this week I have never heard the idiom “jump the shark”. All of a sudden, I hear it 3 times in one week and I don’t know what it means, so I google it …From Wikipedia…"The phrase jump the shark comes from a scene in the fifth season premiere episode of the American TV series Happy Days titled “Hollywood: Part 3,” written by Fred Fox, Jr., and aired on September 20, 1977. In the episode, the central characters visit Los Angeles, where a water-skiing Fonzie (Henry Winkler), wearing swimming trunks and his leather jacket, jumps over a confined shark, answering a challenge to demonstrate his bravery. The series continued for nearly seven years after that, with a number of changes in cast and situations.
Jon Hein, creator of the now defunct website ‘jumptheshark.com’ explained the concept as follows: “It’s a moment. A defining moment when you know that your favorite television program has reached its peak. That instant that you know from now on…it’s all downhill. Some call it the climax. We call it ‘Jumping the Shark.’ From that moment on, the program will simply never be the same.”"
And although I saw the episode as a child, I just never heard the idiom. Weird.