It was supposed to be an invigorating, can't-miss moment: The coolest character on television, clad in a leather jacket and shorts (?!?), would strap on some water-skis to perform a dangerous stunt. But Arthur Fonzarelli, a.k.a. the Fonz, wasn't going to wow the crowd with just any death-defying act, mind you — he was going to leap over a Great White shark. Take that, Jaws! In your face, Pinkie Tuscadero!

When Happy Days forced its most iconic character to stoop to such desperate measures, it left behind a legacy it could not have predicted: a phrase for the moment that a TV series crosses the Rubicon of audience respect, losing both its integrity and the plot. The term "jumping the shark," as coined by Jon Hein for his Website devoted to the devolution of television shows, signals a pivot point in which a writer' room starts resorting to desperate measures to maintain viewers' interest. Such last-gasp measures didn't start with Garry Marshall's nostalgiafest, of course — the less said about the Great Gazoo, the better — but it was the Fonz's date with an aquamarine predator that gave us an iconic moment in which to sum up the beginning of the end.

TV history is littered with JTS moments, and the fact that we're now living in a new Golden Age of Television (TM) hasn't stemmed the tide. So we've brought together a crack team of boob-tube-ologists and asked them to pinpoint some recent examples of unfortunate series shark-jumping. These were all beloved shows that, for one reason or another, took a left turn for the worse. Strap on your waterskis, folks.