Wear some colorful undies & crazy socks for this annual BART flashmob | Sunday

The 12th Annual No Pants Subway Ride will take place on Sunday, January 13, 2013 in San Francisco.

The whole point is for 600+ people to ride BART (and then Muni) without any pants (wearing interesting undies and colorful socks) and to keep a straight face and act completely normal.

The event which takes place in over 15 countries around the world is hosted by prank collective Improv Everywhere.