What started off as a comedy prank in New York in 2002 has blossomed to become a regular event on the global calendar

Subway riders around the world might have noticed something missing when their fellow transit users went trouserless on Sunday for the annual no pants subway ride.

Participants were told to get on trains and act as they normally would and were given an assigned point to take off their pants. They are asked to keep a straight face and respond matter-of-factly to anyone who asks them if they’re cold.

Facebook Twitter Pinterest Travellers in London get into the spirit of the no pants ride on Sunday. Photograph: Pacific Pres/Rex/Shutterstock

The event, organised by the Improv Everywhere comedy collective, started in 2002 in New York with just seven participants.

“We want to give New Yorkers a reason to look up from their papers, from their phones, and experience something that’s a little different than their average run-of-the-mill stuff,” said Jesse Good, one of the event’s organisers.

Facebook Twitter Pinterest A subway rider goes pantless in New York. Photograph: Kathy Willens/AP

Pants-less subway rides took place this year in dozens of cities around the world, including in London, Boston; Berlin; Prague; and Warsaw, organisers said. Philadelphia’s version was sponsored by a laundry delivery service, which asked participants to show up with extra pants or other clothing to donate to charity.

Facebook Twitter Pinterest Young traveller in Prague await their ride. Photograph: Martin Divisek/EPA

Moments before entering a Manhattan station, Peter Saez said it was his third time going pant-less. “People who don’t understand what we’re doing will look at us like we’re doing something bad or wrong,” Saez said. “It’s just for fun. It’s a fun trip, that’s all.”

Facebook Twitter Pinterest Tube travellers in London make themselves comfortable. Photograph: John Stillwell/PA

Toni Carter planned on stripping down to her tight boxers with little polka-dots. “Not very often do I have an opportunity with a group of people to take my pants off and show it whatever I got to show,” Carter said. “I’m entertaining New York City. This is my form of art.”

Facebook Twitter Pinterest Keeping warm in Warsaw on no pants subway ride day on Sunday. Photograph: Jacek Turczyk/EPA

Wei Wei, a student from China who just moved to New York, was curious about the event but was on the fence about whether she was going to go through with taking off her pants. But there was no hesitation for Angela Bancilhon, a tourist from Australia who had her husband and two young sons along for the ride. “It’s fun. Why the hell not?” Bancilhon said. “We’re in NYC. Why wouldn’t you?”