One of my personal favorites is that of the Kappa, a malevolent Japanese water-goblin. Kappas have a bowl-shaped depression on the top of their heads, which is usually filled with water. If you ever meet a Kappa, simply bow politely to him - he will then bow right back to you, which tips the water out of the top of his head. He will then have to go back into the water to refill it, during which time you can get away. Practical knowledge!