No Pants Subway Ride Day hits trains worldwide

Jan. 12, 2014: A passenger stands in between participants as they wait for the train without their pants during the 5th annual "No Pants Subway Ride" in Madrid, Spain. (AP)

Jan. 12, 2014: A man looks at a participant who stands on the train without her pants during the 5th annual "No Pants Subway Ride" in Madrid, Spain. (AP)

If you’re riding the train today and see people without pants – don’t fret – you’re not seeing things.

This Sunday is the annual No Pants Subway Ride Day, which has spread to dozens of countries around the world.

The event was started by theater group Improv Everywhere 13 years ago in New York City, according to the Los Angeles Times, to celebrate peoples’ curiosity and to spread laughter.

On a Facebook page, Chicago’s No Pants organizers recommended people wear “granny panties, boxer briefs, and boy cut underwear,” WGN reports.

Marc Littman, a spokesman for the Los Angeles County Metropolitan Transportation Authority, said pantless riders who are otherwise fully clothed will not be cited for indecent exposure.

"If you're walking around naked, that's a different story,” he told the LA Times.