It is the day of the annual No Pants Subway Ride, where straphangers shed their trousers and finish the trip in their undergarments.
The tradition was started 18 years ago by an improv group in New York City and has spread to public transit lines from San Francisco to Jerusalem.
Organizers call it "an international celebration of silliness."
Participants are supposed to act like they don't know each other and pretend like they are going about their day as normal. All wear winter coats, hats, scarves, and gloves - 'the only unusual thing is their lack of pants'.
Other rides also took place around the world.
(The Associated Press contributed to this report.)
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