This is much like a piece published in the National Lampoon around 1975 on the Wit and Wisdom of Winston Churchill. It was a whole list of Churchill quotes that changed the ending to some vulgar, not-clever insult, but the surprise of it made for comedic effect.
Out of those my favorite is the GBS one. It’s clever; the rest just seem to be “no u.”
But my favorite Churchill quote isn’t an insult at all. The whole story may be made up, but it goes like this:
During a bitterly cold night, one of the coldest of the year, a very important government figure was caught and arrested along with his gay lover for having sex in a public park. The guy was important enough that Churchill was informed about it the next morning because it might develop into a scandal. Churchill’s response: “makes you proud to be British, doesn’t it?”
He called Gandhi a half-naked fakir.
Not exactly a quote, but a joke that was going around after Rudolf Hess’s flight to Britain in May of 1941:
After arriving in London, Hess is finally brought in to see Churchill.
Winston looks him over and says “So, you’re the madman, eh?”
Perplexed, Hess replies “No, sir. He’s at Berchtesgaden.” 