Nancy Astor to Winston Churchill "Sir, if you were my husband, I would poison your tea"
Winston Churchill to Nancy Astor "Madam, if I were your husband, I would drink it."
It is attributed to WC, but is doubted that he actually had that exchange.
In the Cabinet War Rooms, there is a door marked "W.C.". It was assumed that it was Churchill's private office, but actually was just the toilet. The lore goes that he was in there one day when his secretary banged on the door and said: "Mr Prime Minister, the Lord Privy Seal is here to see you." To which Churchill replied: "Tell his lordship that I'm already sealed in my own privy and can only deal with one ***. at a time."