"No shoes, no shirt, no service" is not in play at Cupid's Undie Run, which encourages you to wear your unmentionables for a one-mile jog preceded and followed by a party. What may sound insane in concept is matched by an insanely good outcome, as the nationwide party/race raises money for the Children's Tumor Foundation, an organization committed to ending neurofibromatosis (NF), a disease that causes tumors to grow on nerves throughout the body. In all, the pantsless parties raised $3.5 million last year; organizers hope to raise $4 million this year. You can be a part of a great cause while showcasing your banging body in the process. Cupid's Undie Run takes place from noon to 4 p.m. today at St. Louis Ballpark Village (601 Clark Avenue; www.stlballparkvillage.com). Admission starts at $35.