Photos: 8th Annual No Pants Light Rail Ride in Seattle

SEATTLE -- Thousands of mass transit riders around the world stepped onto buses and subways wearing no pants today.

Why? It's to celebrate silliness.

The No Pants Subway Ride was started by Improv Everywhere in New York in 2002 with seven guys and has grown into an international celebration with dozens of cities around the world participating each year.

In Seattle, riders met at Westlake Park around 2 p.m. Sunday.