WATCH: NYC Commuters Participate In 'No Pants Subway Ride'

MANHATTAN, NY — Thousands of commuters went for a pants-less subway ride on Sunday as part of an annual citywide prank.

The 17th annual "No Pants Subway Ride" saw lots of brave pranksters don their warmest winter clothes, except for pants, to brave the frigid temperatures on subway rides throughout New York City. The annual gag was started by the comedy group Improv Everywhere, and is meant to prank those New Yorkers not in the know: If you're participating in the no pants subway ride, you're supposed to act like everything is normal, and not even acknowledge other pants-less commuters.

Improv Everywhere started the joke with just seven participants in 2002, and it has grown into an annual tradition that draws thousands of brave straphangers willing to bare their legs to the cold. Sunday's weather proved particularly frigid for the jokesters, who organized routes along 11 subway lines throughout the city. The average temperature on Sunday was just 17 degrees, but felt much colder with wind chill.

Improv Everywhere is responsible for lots of other public pranks throughout the city, like when it turned this MTA elevator into an Apple store.

Image credit: Courtesy of Improv Everywhere