Photo by PoPville flickr user Victoria Pickering

For those not familiar it’s for a very good cause – from Cupid’s Undie Run:

“This Valentine’s Day weekend, come put the hilarity in charity with hundreds of half-naked runners taking to the streets in celebration of their fundraising for the Children’s Tumor Foundation.”

Two more shots after the jump.

Photo by PoPville flickr user Victoria Pickering

Photo by PoPville flickr user Victoria Pickering