I was so naive as a kid I used to sneak behind the barn and do nothing.

Carson’s line is a self-deprecating joke built on comic misdirection. “Sneak behind the barn” sets up an expectation of childhood mischief—smoking, drinking, or some forbidden act—only to undercut it with the anticlimax “and do nothing.” The humor comes from the gap between what the audience anticipates and the harmless reality, while also poking fun at youthful innocence and the tendency to mythologize one’s past. It fits Carson’s persona: genial, wry, and willing to make himself the butt of the joke, turning a mundane memory into a punchline about naiveté.