The phrase "Jumping the Shark" entered the vernacular when it was deemed that an episode of "Happy Days" involving the Fonz jumping a shark in an open water pen while on water skis marked the beginning of a rapid decline in both quality and ratings for the show. Now "Jumping the Shark" has come to mean the defining moment of decline in virtually anything.
In the political arena some issues Jump the Shark as soon as they approach the runway. The whole silly issue of Obama's birth certificate was one such issue.
At this point the primary people pushing the issue have gone so gonzo so fast that it's hard to imagine that the claims being made went through a preliminary phase of being almost (but not quite) sane.
After the Supreme Court decided not to hear the case of one Leo Donofrio of New Jersey, challenging Obama's U.S. citizenship, all the stops came out among the wingnuts pursuing this crusade.
In a particularly funny flight of fancy one Bob Schulz of the "We the People" foundation suggested that if Obama didn't end this crisis (presumably by stepping down) Schulz would call a "constitutional convention".
As unlikely as this might seem I'm looking forward to hearing the details of the constitution of the new nation of Wingnuttia.