This was entertainment back in the day. You'd be bored on a Saturday, watching the grass bend in the wind, and then your friend would come over (it would take them four hours to get to you). They'd say, "want to go to town and see the two women who sit on bikes on top of each other?" / "Sure. Just stare at it for a while?" / "Yep." / "How long were you thinking?" / "Maybe six to eight hours." I mean, what else was there to do back then? There wasn't Netflix or anything like that.
How does this idea come up? This doesn't look like a skill you come across by accident, and it doesn't seem like something that would come out of a brainstorm session. I guess it's like asking Steve Jobs how he came up with the iPod. Who really knows at this point.