Self-described as "the largest pantless party and mile(ish) run in the nation," Cupid's Undie Run is not for the faint of heart—or lackluster intimates. But it is a Boise tradition for a good cause. All of the net proceeds from the goosebump-raising dash down Sixth Street will go to the Children's Tumor Foundation to fund research into neurofibromatosis, a genetic nervous system disorder. Participants can think about that heartwarming cause as they strip down to their skivvies (Valentine's Day-themed heart and Cupid-covered sets are encouraged) or throw on flashy costumes for the run, walk or stroll down Sixth and after-party pints at Tom Grainey's. Register online now to save $5 on your fee, then grab some friends and go shop for the perfect panties.