With a new year comes another chance for quirky folks around the world to once again brave cold legs and filthy seats to show off their favorite pair of underoos on public transit. The "impromptu" tradition known as the annual No Pants Subway Ride returns this Sunday, January 13th at 1 p.m. when local pantsless participants drop trou on BART platforms and Muni stops around the city.

Although full details haven't been posted yet, yearly tradition dictates BART and Muni riders while converge on a downtown station before strolling through the streets in search of a photographer to take their picture a drink a fleeting sense of whimsy. Once everyone has achieved a feeling of youthful exhilaration, they all put their pants back on and everyone goes home.

If you're thinking about joining in, remember it's going to be, like, hella cold this weekend. Then stay home and just take your pants off on your couch. Because flashmobs can happen anywhere, you guys, not just in public. And don't try to pretend that sitting on your own couch in your underwear isn't at least a little bit thrilling. (Your roommate could come home at any time!)

If the couch just won't do it for you: keep an eye on the No Pants BART Ride Facebook page for more updates on where to dress down this Sunday. Updates on where to meet (or how to avoid) the pantsless posse on the day of the event will come to you via @NOPantsSF on Twitter.

Previously: Scenes From The "No Pants" BART Ride 2012
Photos: "No Pants" BART Ride 2011