Hundreds of people were spotted travelling on Sunday with no trousers on as a part of the ‘No Pants Subway Ride’ day.

The 15th Annual No Pants subway Ride kicked off at 3:00 p.m. on Sunday and participants all over the world were seeing hopping on the subway without wearing trousers.

The event began in 2002 in New York City with seven members of the improvisational group, Improv Everywhere, known for their flash mobs, boarding the subway without trousers.

By 2006, 150 people had joined, while after 10 years, this trend has spread to countries like Germany, Czech Republic and The UK, proving the trouserless train ride is still alive and well.

‘No Pants Subway Ride’ is always planned in winter, and last year 4,000 people participated in NYC alone.

‘The idea behind No Pants is simple: Random passengers board a subway car at separate stops in the middle of winter without pants. The participants behave as if they do not know each other, and they all wear winter coats, hats, scarves, and gloves. The only unusual thing is their lack of pants,’ Improv Everywhere’s website reads.

Australians also jumped on board the trend with people in Sydney, Brisbane, Adelaide and Melbourne hopping onto public transport on January 10 and posting pictures across social media event pages, as Daily Mail reports.