If you’re riding the subway today, and you notice a fellow straphanger taking off their pants in your car, don't call the cops right away — that person is probably joining in the "No Pants Subway Ride."

The 18th annual ride takes off with straphangers meeting at six stations across the city.

It's organized by Improve Everywhere and they say its a celebration of silliness.

Most people get on the subway with pants before disrobing.

And participants will be cold in their attire today...with temperatures hovering right around freezing.

Along with their tighty whiteys or boxers, riders also have to try to keep a straight face.