Via Flickr:
Copyright © 2011 Deborah M. Zajac. All Rights Reserved.

Thought to be a piece done by famed graffiti artist known as Banksy. In 2010 several pieces thought to be his turned up in San Francisco. This is one.

Nikon D300s| Nikkor 17-35 @ f5.6| 1.3 sec| ISO 800| Manual Mode| Tripod