Hundreds of revelers stripped down to their underwear on Feb. 10 and headed to the North Side for a good cause. Cupid’s Undie Run is held annually to raise money to help fight neurofibromatosis, a genetic condition that causes tumors to form in the brain, spinal cord or nervous system. The mile-long run is held in more than two dozen cities, and this year’s effort raised a reported $140,000 locally.