In Union Square she is posing for photograph at the end of the No Pants Subway Ride.
The No Pants Subway Ride is annual event staged by Improv Everywhere every January in New York City. The mission started as a small prank with seven guys and has grown into an international celebration of silliness, with dozens of cities around the world participating each year.
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.
To maintain the surreal atmosphere, the pantsless commuters were instructed to chat, read and listen to music like they normally would have if clothed.
A flash mob (or flashmob) is a group of people who assemble suddenly in a public place, perform an unusual act for a brief time, then disperse, often for the purposes of entertainment, satire, and artistic expression. Flash mobs are organized via telecommunications, social media, or viral emails.