(photo courtesy from Motorparade)UPDATE:
OK Who knew the American popular culture expression 'jumping the shark', originates from a melodramatic Happy Days scene in which Fonzie jumps over a tank of sharks on water skis. It is now used (according to Wikipedia) to denote the moment when a television series [or anything?] loses its credibility due to predictable repetition or contrived extensions of its theme, usually as a result of the writers being unable to maintain its quality indefinitely.