San Francisco: the city that hates pants. Whether we’re disrobing for the No Pants BART Ride and World Naked Bike Ride or letting it all hang out at Folsom Street Fair, we appreciate the breezy freedom of a pantless party in public. This Valentine’s Day, Cupid’s Undie Run joins the ranks of some of SF’s best scantily clad events in support of The Children’s Tumor Foundation.

The “brief”‘ run on Feb. 14th starts at Pedro’s Cantina, where runners can gain some liquid courage before hitting the streets in their underwear for a mile-long jaunt around the AT&T Park area.

Participants are encouraged to strip down in celebration of funds raised to support children fighting neurofibromatosis (NF), a rare genetic disorder that causes tumors to take over the nervous system, resulting in blindness, deafness, learning disabilities and chronic pain. By hosting an event where runners are asked to bare it all to the elements, organizers hope people will exercise their bravery in support of children with NF who face their fears every day.

Brittney Jordon, San Francisco race director, encourages people to get creative with their undergarments.

“People wear everything from long underwear and thermals to bedroom underwear,” she says. “There’s wings and glitter and garters. They really mix it up.”

Cupid’s Undie Run began in 2010 when co-founder and brother of an NF fighter Chad Leathers and some friends brainstormed ways to raise money for a cure and raise awareness.

“They came up with the idea of running in their underwear in the winter,” Jordon says. “It was D.C. In January.” Despite the freezing temperature, 600 people showed up to that first event, raising $10,000.

This year Cupid’s Undie Run will reach 38 cities across the United States and Australia with the goal of raising $30 million. Another run is schedule for San Jose on Feb. 7.

Photos from Cupid’s Undie Run from throughout the U.S.:

More info on the official Cupid’s Undie Run website.