Every year for the past six years (and about this time of year), the "Great American Slumber Party" has been held in San Francisco.
Folks donning tutus, gorila suits, and santa outfits showed up with their feathery weopons of choice, reports the Mercury News.
"A panda just hit me!" one pillow-wielding man called out as the crowd of revelers, hemmed in by park benches, smacked each other from behind, above and beside.
"I have a hangover from last night, so I figured my head was already hurting," said Katy Medeiros, 47, of Mountain View, who was pulling feathers out of her hair and eye lashes just four minutes after her first thwomp from a pillow. "It's controlled lunacy, isn't it?"
San Francisco's event is at Justin Herman Plaza at 6 p.m. on Valentine's Day.
Below is some footage from today's San Jose fight: