You might find this interesting. From Wikipedia’s ‘Dr. Strangelove’ entry:
Fellow actor James Earl Jones recalls, “He [Slim Pickens] was Major Kong on and off the set—he didn’t change a thing—his temperament, his language, his behavior.” Pickens was not told that the movie was a comedy and was only given the script for scenes he was in, to get him to play it “straight”.
Kubrick biographer John Baxter explains, in the documentary Inside the Making of Dr. Strangelove:
As it turns out, Slim Pickens had never left the United States. He had to hurry and get his first passport. He arrived on the set, and somebody said, “Gosh, he’s arrived in costume!”, not realizing that that’s how he always dressed ... with the cowboy hat and the fringed jacket and the cowboy boots—and that he wasn’t putting on the character—that’s the way he talked.
Lol, that’s a great anecdote! I loved him in 1942!
And...”The Dummy’s right!”