If you are trying to find a last-minute date for Valentine's Day, we know just the place to look. Head down to the Marina District on Saturday afternoon where you'll find plenty of people milling around in their underwear. Don't roll your eyes just yet. It might sound kinda ridiculous, but, hey, you're the one who needs a date. A bunch of charitable-people-turned-exhibitionists are going to be running through the neighborhood in nothing but their underwear for the Cupid Undie Run. Feel free to join the panty party -- just strip down, lace up some running shows, and let your wild side out. The Undie Run starts at 2:30 p.m., which gives all you slackers time to wash a dirty pair of boxer shorts and get down to the race. The organizers of this mile-long run aren't asking much of you (you don't even have to have a nice ass), except maybe to think of the children. As strange as it sounds, this semi-lewd race is going to benefit the Children's Tumor Foundation, an organization that funds neurofibromatosis research. The annual run started in 2010 when a man and his friends planned a race to raise money for his brother's treatment. The first run took place in Washington, D.C., with participants slogging through 6 feet of snow. Fortunately for San Franciscans, it's supposed to be a balmy 55 degrees on Saturday, so you really have no excuse not to get out there. Half-naked people, G-strings, helping kids -- what's not to like about this event? The race doesn't start until 2:30 p.m.; however, The Republic is hosting a pre- and post-run celebration which begins at noon. Now go pick out a fresh pair of heart-covered undies and get your butt ready to run.