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People take part in the annual "No Pants Subway Ride" in the subway in Brussels

People take part in the annual "No Pants Subway Ride" in the subway in Brussels, January 12, 2014. The event involves participants who strip down to their underwear as they go about their normal routine, and occurs in different cities around the world in January, according to its organisers. REUTERS/Eric Vidal (BELGIUM - Tags: TRANSPORT SOCIETY ANNIVERSARY)

No Pants Subway Ride

Subway riders around the world participated in the annual No Pants Subway Ride today, an annual event started by U.S. group Improv Everywhere in 2002. People in New York, Sydney, Beijing, Hong Kong and other cities worldwide rode local metro trains wearing only underwear and shoes below the waist on January 14. Participants are told to look like they're going about their daily lives, and to pretend that they don't know any of the other participants.