2 of 2 added 115 characters in body

Lock the three chains together in the form of the Borromean Rings, and hand me the linked set, then walk away so that you can't see which one I unlock. I unlock the one that I have the key for, separating all the rings. Then, leaving them all unlinked, I relock the chain that I unlocked, and return three unlinked chains to you.

It also works in "reverse", where you give me the unlinked chains, and I return them Borromean-linked.