This annual event started in 2002 in New York. It has now grown with cities around the world joining in.

The concept is simple: participants board the tube without trousers, dressed in winter coats and accessories, while acting as if nothing unusual is happening.聽

To find out more about this event 大象传媒 Radio London's Jumoke Fashola spoke to the creator of the event, Charlie Todd.

(Photo credit: Getty images)