Around San Francisco (and other places, I'm sure - I'm not egotistical enough about my city to think this idea is particularly SF-based) I've seen many different small artworks stenciled and spray painted onto patches of sidewalk. One of my favorites that I've seen lately is a giant squid attacking what looks like a pirate ship:
So, two things:
First, does anyone know who did this? It's great.
Second, how hard do you think it would be to get away with doing one's own stencil-art on government property-aka-sidewalks? I mean, purely for curiosity's sake, of course. Cough.