Very simple. Some one posts a pic of there city, restaraunt, zoo, etc. and picks an item to describe. They then have to describe that item with two discriptive words, without telling anyone what it is. If I wanted to use the Bullet building in the picture below, I would say: "I spy something large and blue." People would then guess what the object is. What someone guesses the correct answer, the poster of the pic will notify them and the winner will post a picture of his own.
I'll start. I spy something small and copper green. (You know, when copper gets wet it turns green, that color).
I forgot to mention, please dont be too specific. If my object was "the white car on top of the parking garage", and some one guessed "a white car" they would still be the winner even though I have multiple white cars in my city.