If you plan to use the subway today, make sure you remember your MetroCard and keys, but you can leave the pants at home.

Today is the 19th annual "No Pants Subway Ride."

It was started by an improv comedian named Charlie Todd in 2002 who posted videos of the event on YouTube. Since then, it has spread around the world.

Participants are told to gather at Foley Square at 3 p.m. this afternoon, where they'll be assigned a specific train line.

From there, pantless riders are told to act casual and not speak to other participants.

If faced with questions, they're supposed to say they forgot to wear pants, and only feel a little cold.