It's happy! It's fun! It's Faceball!
Good design is everywhere. Witness the above graphical primer teaching newbies how to play Faceball, an office game invented by a couple guys over at Flickr. The concept is simple: Two players take turns trying to hit each other in the face with an inflatable ball. The rules are a bit more complex, but the graphic quickly makes them easy to understand.
(P.S. Check out the video primer on the Faceball Web site. Good stuff.)