Here in Boise, ID we have a little "game" we like to play called velocache. All you have to do it stuff some goodies into a small container, take it to any location you'd like to share with others and hide it. Once hidden you take a picture of the cache itself, and a few prospective photos to use as hints for where you hid the cache.

I'm curious on what other kind of games are played in other cities in and maybe outside of the states?