“My Grandma McLain had a superstition about folding her money. And she believed if you folded it in half that you would always have money. And that’s something I’ve always done with my money ever since I was a little kid. Never bothered to look up that, uh, belief. I don’t know what the origin was, um, I don’t know if it’s an old German belief, or superstition.”
This is a classic example of superstition gone rampant. An idea that someone upheld that was then passed on to someone else, but with no one really knowing its origin or whether there is any real sound reason behind it.