Scores of SkyTrain riders were travelling by the seat of their underpants on a chilly Sunday afternoon for the fourth-annual No Pants SkyTrain Ride.

Starting at 1 p.m., riders doffed their pants in an effort to spread a little stripped-down mirth to beat the winter blahs.

According to social media sites spreading the word, riders were encouraged to board their train cars and then strip out of their pants as soon as the doors closed.

Tips for explaining the unusual behaviour included telling fellow passengers they simply forgot their pants, and insisting it’s a coincidence others made the same mistake and boarded the train minus the lower half of their wardrobe.

For those feeling a little shy about the stunt, it was suggested modesty could be upheld by wearing two pairs of underwear.

On the Vancouver No Pants Skytrain Ride Facebook page, 199 had confirmed their intention to take part.

“This is the best way to start off a new year. Count me in, and count my pants out,” posted one confirmed participant.

“I am so getting granny panties for this,” posted another. “This is priceless — how can I not do it?”

The No Pants Subway Ride is an annual event organized by New York City prank group Improv Everywhere, whose motto is “We cause scenes.”

The initial ride took place in the Big Apple in 2002 when seven brave riders unzipped.

According to the group’s website, the pant-less ride has today spread to 60 regional rides in more than 25 countries.