It's winter, and people are wearing
their underwear on the subway.
The group Improv Everywhere stages "scenes of chaos and joy in public places." Since 2002, every January they've done a No Pants! Subway Ride in New York City. This year, 3,500 people took off their pants and rode the subway. Many thousands also participated in cities around the world.
Much fun comes from the reactions of the other subway riders, who aren't just seeing a single person who's not wearing pants, they're seeing a whole lot of people who aren't wearing pants.
No Pants Subway Ride 2011>>
No Pants Subway Ride - a history with video>>