A poster announcing the Valentine's Day Pillow Fight Club event in San Francisco. No organizer is listed on the poster. The event was organized somewhat like a flash mob: Word went out on e-mail lists, on social networking sites like Tribe.net and through general Internet word of mouth.
These pillow fight participants have no shortage of enthusiasm for the event.
Hundreds of pillow fighters have at it in San Francisco's Justin Herman Plaza on Tuesday evening.
Countless feathers set loose from the battered pillows make it look like snow is falling.
A woman at the Pillow Fight Club event prepares to take down an opponent.
Being in the thick of things meant getting pounded by pillows and inhaling feathers.
One man uses his pillow to send a message to would-be attackers.
When the pillow fight was over, the cleanup was only just beginning.