Monday morning saw the world's 12th annual "no pants subway ride" (that's trousers and the Tube to you and me), and bearing in mind most of London woke up to a teeth-chattering 0 degrees, didn't we do well!

Trembling buttocks, knocking knees and acres of gooseflesh were on display as commuters braved the snowy weather to come together for the New York-based event which has since gone global.

Staged by entertainment collective Improv Everywhere, the mission began as a prank between seven men and is now, in its own words, "an international celebration of silliness".

no pants day

Stiff upper lip: London commuters join in Improv Everywhere's 'no pants subway ride' (not sure what he's doing on Tulisa's face, mind)

There is just one simple rule, the website explains:

Random passengers board a subway car at separate stops in the middle of winter without pants. The participants do not behave as if they know each other, and they all wear winter coats, hats, scarves, and gloves. The only unusual thing is their lack of pants.

Thousands of people in more than 50 cities across the globe were expected to take part in the chilly practical joke, it added.

Just remember, if you're celebrating in Britain, you have to keep your underpants ON. Pants in America means trousers. Just checking, don't want anything getting lost in translation now...

Did you take part in no pants on the tube day? Send us your images and we'll publish them ukpicturedesk@huffingtonpost.com

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  • No Pants Day 2013, London, Britain - 13 Jan 2013. Commuters on the London Underground not wearing any trousers as part of the annual 'No Pants Day'. (Credit: Rex)

  • No Pants Day 2013, London, Britain - 13 Jan 2013. Commuters on the London Underground not wearing any trousers as part of the annual 'No Pants Day'. (Credit: Rex)

  • No Pants Day 2013, London, Britain - 13 Jan 2013. Commuters on the London Underground not wearing any trousers as part of the annual 'No Pants Day'. (Credit: Rex)

  • No Pants Day 2013, London, Britain - 13 Jan 2013. Commuters on the London Underground not wearing any trousers as part of the annual 'No Pants Day'. (Credit: Rex)

  • No Pants Day 2013, London, Britain - 13 Jan 2013. Commuters on the London Underground not wearing any trousers as part of the annual 'No Pants Day'. (Credit: Rex)

  • No Pants Day 2013, London, Britain - 13 Jan 2013. Commuters on the London Underground not wearing any trousers as part of the annual 'No Pants Day'. (Credit: Rex)

  • No Pants Day 2013, London, Britain - 13 Jan 2013. Commuters on the London Underground not wearing any trousers as part of the annual 'No Pants Day'. (Credit: Rex)

  • People ride the subway pantless on January 13, 2013 in New York City. Thousands of people participated in the 12th annual No Pants Subway Ride, organized by New York City prank collective Improv Everywhere. During the afternoon winter event, participants boarded separate subway stops and removed their pants, pretending that they did not know each other. The event, refered to as a "celebration of silliness" is designed to make fellow subway riders laugh and smile. (Photo by John Moore/Getty Images)

  • Participants in the annual "No Pants Subway Ride" ride a train in Mexico City, Sunday, Jan. 13, 2013. (AP Photo/Marco Ugarte)

  • Carrying a bike, a participant in the annual "No Pants Subway Ride" transfers to another train in Mexico City, Sunday, Jan. 13, 2013. (AP Photo/Marco Ugarte)

  • A soldier takes off his pants while riding the subway on January 13, 2013 in New York City. He and thousands of others participated in the 12th annual No Pants Subway Ride, organized by New York City prank collective Improv Everywhere. During the afternoon event, participants boarded separate subway stops and removed their pants, pretending that they did not know each other. The event, refered to as a "celebration of silliness" is designed to make fellow subway riders laugh and smile. (Photo by John Moore/Getty Images)

  • People ride the subway pantless on January 13, 2013 in New York City. Thousands of people participated in the 12th annual No Pants Subway Ride, organized by New York City prank collective Improv Everywhere. During the afternoon winter event, participants boarded separate subway stops and removed their pants, pretending that they did not know each other. The event, refered to as a "celebration of silliness" is designed to make fellow subway riders laugh and smile. (Photo by John Moore/Getty Images)

  • People ride the subway pantless on January 13, 2013 in New York City. Thousands of people participated in the 12th annual No Pants Subway Ride, organized by New York City prank collective Improv Everywhere. During the afternoon winter event, participants boarded separate subway stops and removed their pants, pretending that they did not know each other. The event, refered to as a "celebration of silliness" is designed to make fellow subway riders laugh and smile. (Photo by John Moore/Getty Images)

  • People ride the subway pantless on January 13, 2013 in New York City. Thousands of people participated in the 12th annual No Pants Subway Ride, organized by New York City prank collective Improv Everywhere. During the afternoon winter event, participants boarded separate subway stops and removed their pants, pretending that they did not know each other. The event, refered to as a "celebration of silliness" is designed to make fellow subway riders laugh and smile. (Photo by John Moore/Getty Images)

  • People ride the subway pantless on January 13, 2013 in New York City. Thousands of people participated in the 12th annual No Pants Subway Ride, organized by New York City prank collective Improv Everywhere. During the afternoon winter event, participants boarded separate subway stops and removed their pants, pretending that they did not know each other. The event, refered to as a "celebration of silliness" is designed to make fellow subway riders laugh and smile. (Photo by John Moore/Getty Images)

  • People ride the subway pantless on January 13, 2013 in New York City. Thousands of people participated in the 12th annual No Pants Subway Ride, organized by New York City prank collective Improv Everywhere. During the afternoon winter event, participants boarded separate subway stops and removed their pants, pretending that they did not know each other. The event, refered to as a "celebration of silliness" is designed to make fellow subway riders laugh and smile. (Photo by John Moore/Getty Images)

  • Participants in the annual "No Pants Subway Ride" ride a train in Mexico City, Sunday, Jan. 13, 2013. (AP Photo/Marco Ugarte)

  • People ride the subway pantless on January 13, 2013 in New York City. Thousands of people participated in the 12th annual No Pants Subway Ride, organized by New York City prank collective Improv Everywhere. During the afternoon winter event, participants boarded separate subway stops and removed their pants, pretending that they did not know each other. The event, refered to as a "celebration of silliness" is designed to make fellow subway riders laugh and smile. (Photo by John Moore/Getty Images)

  • Participants in the annual "No Pants Subway Ride" transfer to another train at a subway station in Mexico City, Sunday, Jan. 13, 2013. (AP Photo/Marco Ugarte)

  • Participants in the annual "No Pants Subway Ride" wait to get a train at a subway station in Mexico City, Sunday, Jan. 13, 2013. (AP Photo/Marco Ugarte)

  • Participants in the annual "No Pants Subway Ride" wait to get a train at a subway station in Mexico City, Sunday, Jan. 13, 2013. (AP Photo/Marco Ugarte)

  • Participants in the annual "No Pants Subway Ride" ride a train in Mexico City, Sunday, Jan. 13, 2013. (AP Photo/Marco Ugarte)

  • A soldier takes off his pants while riding the subway on January 13, 2013 in New York City. He and thousands of others participated in the 12th annual No Pants Subway Ride, organized by New York City prank collective Improv Everywhere. During the afternoon event, participants boarded separate subway stops and removed their pants, pretending that they did not know each other. The event, refered to as a "celebration of silliness" is designed to make fellow subway riders laugh and smile. (Photo by John Moore/Getty Images)

  • A man, wearing underwear, records video of another man, also wearing underwear, during the annual "No Pants Subway Ride" at a subway station in Mexico City, Sunday, Jan. 13, 2013. (AP Photo/Marco Ugarte)

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  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

  • Photo by <a href="http://paynie.net/" target="_hplink">Steve Payne</a>.

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  • No Pants Metro Ride -- Washington, D.C. (2011)

  • No Pants Metro Ride -- Washington, D.C. (2010)

  • No Pants Subway Ride -- New York City (2008)

  • No Pants Subway Ride -- New York City (2009)

  • No Pants Subway Ride -- New York City (2010)

  • No Pants Subway Ride -- New York City (2011)

  • No Pants Subway Ride -- Los Angeles (2010)

  • No Pants Subway Ride -- Toronto (2010)

  • No Pants Subway Ride -- Chicago (2011)

  • No Pants Subway Ride -- Barcelona (2010)