Commuters taking part in the annual international No Pants Subway Ride on a London underground train on Sunday. Started in 2002 with only seven people taking part, the day is now marked in more than 60 cities around the world. The idea behind the No Pants day is for random passengers to board subway cars at separate stops in the middle of winter without wearing trousers. Participants wear all of the usual winter clothing on their top half such as hats, scarves and gloves and do not acknowledge each other's similar state of undress.