Especially in San Francisco where people go totally nude. Is it some kind of demonstration against something? What? This is from SFGate:
MUNI commuter, Brian Lum, rides along with “No Pants” participants, Brooke Sheffer, left, and Linda Hubbard, on January 13, 2013 in San Francisco, Calif. The event, which takes place in various subways around the world is hosted by the group Improv Everywhere, and asks participants to wear no pants but to don colorful underwear and socks.”
I think Bob Parks over at Black and Right said it well. He said that the trouble with this kind of thing is the same problem that exists with nudism: The people who do it are not people you want to see naked.