Organized by Improv Everywhere, a New York City-based prank collective, the No Pants Subway Ride is now in its eleventh year. During the 2012 iteration, Improve Everywhere claims that nearly 4,000 people participated in New York with tens of thousands more participating in 59 cities in 27 countries around the world.
"The idea behind No Pants is simple: Random passengers board a subway car at separate stops in the middle of winter without pants. The participants do not behave as if they know each other, and they all wear winter coats, hats, scarves, and gloves. The only unusual thing is their lack of pants."
According to the Daily News, "It's like commuting, but without the pants."
