If you're ever dying to know whether an acquaintance wears boxers or briefs, invite him to the Cupid's Undie Run. (Unless he's a coworker, in which case that might be weird.) But that's all you have to wear to the annual skivvies-friendly run through downtown Denver. To raise money for the Children's Tumor Foundation, the city's brave (and probably cold) relaunched their sexy fundraiser this weekend at Stoney's Bar & Grill. Continue reading for photos of the best-dressed (or maybe least-dressed) and visit our full slide show for more.