The phrase jumping the shark gets tossed around when a show or popular figure does something that is considered ridiculous, out of character, gimmicky or all of the above. It comes from an old episode of Happy Days when Fonzie jumps over a shark while water skiing.
I read an article by Fred Fox, Jr, who wrote that particular episode. He doesn’t think it is deserving of the title. But he admits:
…it’s clear that “jump the shark” is no mere fad. It has become a part of the American lexicon.
I wonder, how far a person or even a character in a show or novel can go outside their comfort zone and still be convincing.
Sharknado was silly gimmick but it was also entertaining and very popular. While there were plenty of shark jokes flying, I didn’t see anyone say that SyFy Channel had jumped the shark with this one. I think that’s because no one expected a scary Jaws kind of movie. The promos showed a campy, ridiculous premise and followed through.
So I think that is the answer. Jumping the shark is an accusation of false advertising. If I’m going to spring something new on people, something out of character or implausible I’d better give some warning.