If you're on the Metro this Sunday and you see hordes of pants-less riders, don't be too alarmed: It's just the sixth annual No Pants Metro Ride.

For those who don't know, the event is exactly as it sounds; from 1 p.m. to 3 p.m. this Sunday afternoon, Angelenos will meet at several stations across the Metro grid and ride the lines in their underwear. It was first put on by Improv Everywhere in New York City, and it has grown into a global phenomenon over the years.

According to a "top secret" dossier (ha) put out by GuerilLA, the stops where the pants-less riders are expected to convene are the Gold Line's Atlantic and Sierra Madre Villa stations, The Purple Line's Wilshire/Western station, The Red Line's North Hollywood station and the Expo Line's Culver City station.

Judging from last year's pictures and the projected turnout on the event's Facebook page, there's going to be a good amount people who will strip to their skivvies while riding the rails.