Nevermind the Chill: No Pants Subway Ride-2019 Takes Over the World

Particpants in the "No Pants Subway Ride" flash mob in a NYC Subway station.

Passengers without trousers during the “No Pants Subway Ride” in Amsterdam, The Netherlands, on 13 January 2019. The No Pants Subway Ride is a global annual event where people ride public transport while not wearing any trousers to surprise other passengers.

A janitor looks on at a participant in the "No Pants Subway Ride" checking a map on 13 January 2019 at a subway station in Berlin. The No Pants Subway Ride is a global annual event where people ride public transport while not wearing any trousers to surprise other passengers.

People pose for a photograph at Canada Water as they take part in the annual “No Trousers On The Tube Day” (No Pants Subway Ride) on the London Underground in central London on 13 January 2019. Starting in 2002 with only seven participants, the day is now marked in many cities around the world. The idea behind "No Pants" is that random passengers board a subway car at separate stops in the middle of winter, while not wearing trousers. The participants wear all the usual winter clothing on their top half such as hats, scarves and gloves and do not acknowledge each other's similar state of undress.

A particpant in the "No Pants Subway Ride" flash mob in a NYC Subway station.

Women participating in the annual "No Pants Subway Ride" remove their jeans in the borough of Manhattan, New York City, U.S., 13 January 2019.

Participants in the 18th Annual "No Pants Subway Ride" travel in the subway on 13 January 2019 in New York. The "No Pants Subway Ride" is an annual event started in 2002 by Improv Everywhere in New York, the goal of which is for riders on the subway train to dress in normal winter clothes without pants while keeping a straight face.

People participate in the annual "No Pants Subway Ride" in the borough of Manhattan, New York City, U.S., 13 January 2019.

Passengers take pics of the "No Pants Subway Ride" flash mob's participants on the NYC Subway.

A woman waits for a train while participating in the annual "No Pants Subway Ride" in the borough of Manhattan, New York City, U.S., 13 January 2019.

Participants in the 18th Annual "No Pants Subway Ride" travel in the subway on 13 January 2019 in New York. The "No Pants Subway Ride" is an annual event started in 2002 by Improv Everywhere in New York, the goal of which is for riders on the subway train to dress in normal winter clothes without pants while keeping a straight face.