Bob-omb scare

Something must be up with all this random game graffiti. First Pac-Man was sighted in Buffalo, and now Bob-omb of Super Mario fame, is right here in Los Angeles. I know this is most likely the handiwork of some wily gamer armed with spray cans and a rabid imagination, but for a moment, I find myself fantasizing about some nutty collective that travels the world over marking it with bits of video game history. A secret society, if you will. Who are they? What do they do? Where can you find them? Have they finished every game ever made? NO ONE KNOWS.