Hundreds of people braved the cold and took part in the annual No Trousers Tube Ride on Sunday (January 7).
More than 400 took part in the event, where people ride the London Underground network half naked.
Men and women ignored the chilly 3C temperature to take part, with organisers saying its sole purpose is "to make others laugh and smile."
The brave souls met near Westminster at 3pm, before removing their clothing and placing it in their rucksacks.
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They were spotted at Liverpool Street and Bond Street stations, before enjoying an after-party.
Writing on its Facebook group, the organisers of the London event - The Stiff Upper Lip Society - said those participating should act normal while travelling.
It said: "You can wear fun underwear if you like, but nothing that screams out, 'I wore this because I’m doing a silly stunt.'
"Wear two pairs of underwear if it makes you feel more comfortable.
"Don’t wear a thong or anything else that might offend people.
"Our aim is to make people laugh, not p*** them off."
The ninth annual event was part of the worldwide No Pants Subway Ride which began as a small prank in New York 16 years ago - when just seven people took part - and has since spread to more than 60 cities around the globe.
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