Most biographies and articles on John Jay portray him as a very serious guy. While reading his correspondence, one can find his humorous side. Walter Stahr (in his book "John Jay: Forgotten Founder") on page 164 relates how Adams said that the three men lived together in perfect good humor. Something to which I attribute the good humor in that instance is the presence of Sally and Maria Jay. Sometimes negotiations would carry on in the hotel room in Paris. Their entertainment was young Maria. Richard Oswald (one of the British negotiators) said on August 15 and 17, 1782 that he was expecting Jay to be serious "But I was agreeably disappointed having found him in the best humour, and disposed to enter into a friendly discussion on the Business I came about."
An example of Jay's humor is seen in a comment he had about the Spanish post office opening his mail. "If my Spanish is not correct, I hope the post office will correct it." (John Jay to Montmorin, 19 July, 1782 found in Richard Morris' "John Jay, The Winning of the Peace", p. 245).
While on the run from the British and Tories in Fishkill in 1777 Jay said that "shoemakers are as scarce here as saints were in Sodom." (Walter Stahr. John Jay, p. 68. Jay made quite a few comments about the dreaded flea. Fleas were a real problem for Jay and the other Supreme Court justices as they had to travel the circuit. Fleas were one of the reasons why Jay accepted the governor position in New York and left the Supreme Court. John Adams nominated him to return to the Supreme Court after he served six years as governor of New York but Jay turned it down, he did not want the bedbugs to bite.