The global "No Pants Subway Ride" was observed Sunday, in 50 cities around the world.
Young and old, men, women and children got in on the 12th annual round of the prank held once a year, the well-ventilated movement said on its website.
Considered by some to be the original flash mob, the No Pants Subway Ride originated in New York City in 2002. It has since spread to over 60 cities, including London, Sydney, Berlin, Shanghai and Paris.
- files from AFP