Passengers on the metro in Prague took part in the 'No Pants Subway Ride', an annual event which is now in its 20th year. Passengers were travelling in just their underwear from the waist down. Started in New York, the 'No Pants Subway Ride' has now grown into an international event with 20 cities taking part worldwide. Trouser-less riders also appeared in other cities around the world, including London and New York. According to an organiser Facebook page, its basically a light-hearted, fun event for no reason other than to make people smile and laugh at each other, instead of staring into their phones.