being able to fold a simple origami crane at any given moment is a very satisfying skill, unfortunately, it fades if you don't practice it enough. I learned how to fold origami cranes at least 3 times in my life
So it's like riding a bike, except you forget how to do it.
With me it is solving the Rubik's cube. I must have relearned David Singmaster's a couple of times but after a year or two of not solving one, I easily forget.