Many years ago—it was at least 15; might’ve been more than 20—I called up the cartoonist Peter Mueller to ask about a cartoon of his called “Mental Floss.”
I don’t remember what I needed to know. I might have just liked it and wanted to know where the idea came from. But I remember what he said.
“Oh, it’s not original,” Mueller told me. “I don’t even know who came up with it first.”
P.S. Mueller is still one of the preeminent one-panel cartoonists working today, and you can buy various swag depicting the “Mental Floss” image—and several variations of it, none of those I found by Mueller—from various swag outlets, both ethereal and ephemeral.