Commuters in some 60 cities braved public transportation in their undies for the stunt, which has gone global since its first staging by US group Improv Everywhere in New York in 2002.
The premise is simple: participants convene on a given route on a designated day every year without trousers on, and ride the rails (or road) for shock value and laughs.
“It is just about fun, and providing a laugh and a smile,” said Charlie Todd, who created the event 12 years ago when just seven people took part.
Act “normal. Remember to keep a straight face,” Todd instructed participants in the Big Apple — some 3,000 to 4,000 people this year aged three months to 71.
“If somebody tells you you have no pants, just say you forgot, and yes it’s cold, yes it’s unfortunate,” he said.
Underpants must be worn and, although flashy designs are allowed, organizers prefer those involved to look – at least from the waist-up – as though they are going about their daily lives in an effort to up the impact on bystanders.
Uniforms and business suits are encouraged to amplify the lower-half effect, as are props – bicycles, prams, shopping bags or even a briefcase.
Seven New York subway stops were designated for this year’s stunt, with the group planning to reconvene ultimately at Union Square in Manhattan.
“It’s a bit chilly, but it is fun,” said Pedro, in red underwear and socks, wearing a hat and carrying a briefcase, as he stood on a subway platform.
A woman in her thirties donning briefs and talking on her cell phone prompted amused glances from passersby, with one older woman sporting a perplexed stare.