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xkcd #2869: Puzzles
(imgs.xkcd.com)
Alt text:
Why couldn't the amulet have been hidden by Aunt Alice, who understands modern key exchange algorithms?
I had one friend who was obsessed with these idiotic "lateral thinking" puzzle books, because she'd read them to us and then pretend like she had figured out the completely ridiculous scenarios from the start.
I had an elementary school teacher who would do these puzzles with our small class.
It was much better than your situation though: he would already know the solution and basically we took turns asking him yes or no questions until we figured it out.