A man walks past a group of women without pants at a rail station during the annual No Pants Light Rail Ride organized by the Emerald City Improv group in Seattle, Washington

On Sunday, riders of public transportation may have been surprised by the amount of pantless passengers who accompanied them on their commute.

Yes, yesterday was No Pants Subway Ride day.

What started off as a small gag put on by New York improv group Improv Everywhere in 2002 has since blossomed into being an international phenomenon.

The annual tradition, which as its name suggests, involves riding public transportation without pants, is now celebrated in “nearly 60 cities worldwide in 26 countries.”

It is a day to partake absurdity and fun according to Improv Everwhere founder Charlie Todd.

“It’s meant to be a positive thing to make people laugh and smile,” Todd said.

Here’s some of the more amusing photos of the day’s silliness courtesy of the New York Post and WUSA 9, spanning from New York to London to Prague.

[New York Post][WUSA9]