Supposedly this joke was told by Prime Minister Netanyahu. The context for the joke is that Bibi has long complained that the press goes out of its way to portray him in a negative manner:
"Do you know what the headlines in the papers would be, if I was to go to Galilee and walk on the water of the kinneret?"Bibi does not know how to swim".
Some quick Googling showed that this is far from an original joke.
Sarah Palin version: ; If Sarah were to walk across the waters of the Sea of Galilee, the media would triumphantly proclaim “SARAH CAN’T SWIM!!!
Helmut Kohl version: My good friend Stefan Claass from Mainz once told me a joke which was doing the rounds in Germany when Helmut Kohl was Chancellor having a tough time of it. “God could see that Helmut needed a little help and so sent an angel to him. ‘Helmut you are having a rough time’, said the angel, ‘God will grant you one wish’. Helmut replied, ‘great, I would like to walk on water.’ The wish was duly granted. Two Germans were standing looking across the Rhine River, they saw the Chancellor walking on water, one said to the other, ‘Look at that he can’t even swim!’”
Bill Clinton Version: Which reminds me, of course, of the joke told about President Bill Clinton, who, on his visit to Israel, took a boat ride in the Sea of Galilee, with the press boat following behind. When Hillary’s hat fell, President Clinton walked on water and retrieved it. The press’ reaction: “Clinton can’t swim.”
Conclusion: The joke is still funny. Bibi finds himself in some good company.