A group of four pirates has a treasure chest and one unique lock and key for each pirate. Using hardware that is probably already lying around their ship, they want to protect the chest so that any subset of three of these pirates can open the chest using their respective locks and keys, but no two pirates can. How do they set this up?

What will be an ideal response?

Each pirate uses his lock and key to lock down one of the four sides of the lid to
the chest. If any three pirates open their latches, they can lift the top by essentially using
the fourth (locked) latch as a hinge. (There are other solutions possible as well.)