Runners dash through downtown L.A. in their undies — for a good cause, of course — at this annual Valentine's Day-themed run. The fun run is a 1-mile dash that's sandwiched between party time at the Belasco Theater. Held in 35 U.S. cities and four cities in Australia, Cupid's Undie Run is the world's largest organized underwear run, focused on raising money to benefit the Children's Tumor Foundation (CTF). To date, Cupid's Undie Run has raised more than $8 million for CTF. All photos by Kelsee Becker.