Thought riding Metro was uncomfortable before? Sunday is No Pants Day.

Nudity is prohibited by law on the Metro subway system (and on the streets of the nation’s capital), but nowhere is it written that you have to wear pants.

In defiance of logic — the low temperature is forecast to be 29 degrees — a bunch of people plan to forgo wearing pants (or skirts) while riding Metro this Sunday, the annual ritual of No Pants Day. It’s all part of a delightful plan of non-compliance with societal norms that began 14 years ago in New York City by the group Improv Everywhere. In New York, people who dress in peculiar fashion generally get a yawn, if anybody notices them at all. D.C., however, has a greater sense of Southern propriety than most of its inhabitants are willing to admit.

No Pants Day on Metro the past couple of years was great fun for the pant-less, but confounding for those not in the know who just happened onto the train only to be surrounded by men and women in their skivvies.

This year the event will take place in almost 40 cities worldwide. Participants in Buenos Aires (forecast low of 72 degrees), Hong Kong (63 degrees) and Brisbane (64 degrees) are likely to be more eager to doff their pants than folks in Minneapolis (minus 9), Helsinki (13) or Stockholm (22).

In D.C., 595 people have noted their interest on the group’s Facebook page and 229 say they are going. They plan to meet at 3 p.m. Sunday at Hancock Park by the L’Enfant Plaza Metro station (at the corner of 7th, C, and Maryland SW).

The no-pants people have a brief tutorial for rider wanna-bes on their Facebook page:

“We will have a brief pre-ride meeting starting at 3 p.m., and soon afterward we’ll release people into the Metro to ride. We know it can be hard not to dance and celebrate a lack of pants, but we encourage people to maintain the original spirit: Act as if it’s any other day. You just happen to be without pants. Maybe you forgot them. Maybe you hadn’t even noticed. Maybe, despite the assertions of those around you, you’re pretty sure you have them on.”

“Some tips: bring a backpack or a bag to hide pants in. Make sure your SmartTrip or paper farecards are ready to go in advance. Some are welcome to depants while still outside, but in general most will tend to depants as soon as they board their first train, especially because those initial reactions from fellow passengers are the best part.”

“And if any figure of authority tells you to put your pants back on: do as they say. Fortunately, Transit Police have been in great spirits every year (we’ve been doing this since 2008!), and we’ve always had a great crowd joining us for the ride.”

“For newcomers wondering ‘Why?’ we instead ask ‘Why not?'”