More than 300 people braved the streets of Midtown, the weather and numerous onlookers, as they stripped down to their underwear for a jog around town. Those people were taking part in Cupid's Undie Run.

Cupid's Undie Run is a fundraising event for the Children's Tumor Foundation. The event started in Washington, D.C., in 2010. This year's event grew to 17 cities in the United States. There was a Cupid's Undie Run in Sydney, Australia, too.

GALLERY: Cupid's Undie Run

"What started as a small joke between friends in (Washington) has turned into a nationwide fundraising phenomenon," race organizer Hannah Thompson told Nelson's News on wsbtv.com "We're not stopping until we find a cure!"

More than 8,000 runners participated in Cupid's Undie Runs this year. Each runner tries to collect sponsorship money for participating in the run. Thompson said the runs have raised more than $1,000,000 in 2013. More than $40,000 was collected from pledges in Atlanta.

To learn more about the organization, check out www.cupidsundierun.com.