Things you learn as a kid and then re-learn when you have them

I was handed a Slinky which was doing a pretty good impression of a knotted-up ball of wire. It took me about 10 minutes to figure out methods that would resolve tangles in a helix and then another 10 to straighten-out the whole thing.

As soon as I was done, I realized how much a waste of time it was: The thing is so deformed now that I doubt any play can be had from this toy. Unless you count the puzzle game called, "tangle-up the slinky and then figure out how to untangle it".