Walking around the city today, I happened upon a few of these awesome signs from the "Metropolitan Etiquette Authority." Turns out it's a project from artist Jay Shells (who put up these genius subway etiquette posters last year—yes, people really do clip their nails on the subway).
The signs are pretty great, and hit on two of my pet peeves. First, why is it ok for smokers to litter? And second, watch where you're going, I'm walkin' here!