People take part in the No Pants Subway Ride in Berlin January 11, 2015. The No Pants Subway Ride is an annual event that has become a global celebration of bare thighs. The “celebration of silliness” is designed to make other Tube riders smile. (Photo by Hannibal Hanschke/Reuters)

People take part in the No Pants Subway Ride in Berlin January 11, 2015. (Photo by Hannibal Hanschke/Reuters)

People take part in the No Pants Subway Ride in Berlin January 11, 2015. (Photo by Hannibal Hanschke/Reuters)

People take part in the No Pants Subway Ride in Berlin January 11, 2015. (Photo by Hannibal Hanschke/Reuters)

People take part in the No Pants Subway Ride in Berlin January 11, 2015. (Photo by Hannibal Hanschke/Reuters)

People take part in the No Pants Subway Ride in Berlin January 11, 2015. (Photo by Hannibal Hanschke/Reuters)

Passengers without pants wait for the subway train during “The No Pants Subway Ride” in Mexico City January 11, 2015. The event, the fifth organized in Mexico, is an annual flash mob and occurs in different cities around the world, according to its organisers. (Photo by Edgard Garrido/Reuters)

A passenger without pants waits for the subway train during “The No Pants Subway Ride” in Mexico City January 11, 2015. (Photo by Edgard Garrido/Reuters)

A passenger without pants ride a subway train during “The No Pants Subway Ride” in Mexico City January 11, 2015. (Photo by Edgard Garrido/Reuters)

A pair of lovers without pants ride a subway train during “The No Pants Subway Ride” in Mexico City January 11, 2015. (Photo by Edgard Garrido/Reuters)

A woman walks past passengers without pants waiting for the subway train during “The No Pants Subway Ride” in Mexico City January 11, 2015. (Photo by Edgard Garrido/Reuters)

Passengers without pants wait for the subway train during “The No Pants Subway Ride” in Bucharest January 11, 2015. The event, the first organized in Romania, is an annual flash mob and occurs in different cities around the world, according to its organisers. (Photo by Radu Sigheti/Reuters)

Passengers without pants sit inside a subway train during “The No Pants Subway Ride” in Bucharest January 11, 2015. (Photo by Radu Sigheti/Reuters)

A participant takes his pants off as he prepares for “The No Pants Subway Ride” in Bucharest January 11, 2015. (Photo by Radu Sigheti/Reuters)

A participant reads a book as he waits for a train during “The No Pants Subway Ride” in Bucharest January 11, 2015. (Photo by Radu Sigheti/Reuters)

A participant stands next to a subway guard during “The No Pants Subway Ride” in Bucharest January 11, 2015. (Photo by Radu Sigheti/Reuters)

A man checks his mobile phone between passengers without pants inside a subway train during “The No Pants Subway Ride” in Bucharest January 11, 2015. (Photo by Radu Sigheti/Reuters)

A passenger without pants stands inside a subway train during “The No Pants Subway Ride” in Bucharest January 11, 2015. (Photo by Radu Sigheti/Reuters)

A man looks on at two passengers without pants during “The No Pants Subway Ride” in Bucharest January 11, 2015. (Photo by Radu Sigheti/Reuters)

Passengers without pants wait for the subway train during “The No Pants Subway Ride” in Bucharest January 11, 2015. (Photo by Radu Sigheti/Reuters)

A passenger not wearing pants waits for a subway train during the “No Pants Subway Ride” in Prague January 11, 2015. The event is an annual flash mob and occurs in different cities around the world in January, according to its organisers. (Photo by David W. Cerny/Reuters)

Passengers (R) not wearing pants stand in a subway train during the “No Pants Subway Ride” in Prague January 11, 2015. (Photo by David W. Cerny/Reuters)

Passengers not wearing pants walk up the stairs through a subway train transfer tunnel during the “No Pants Subway Ride” in Prague January 11, 2015. (Photo by David W. Cerny/Reuters)

A passenger (R) not wearing pants waits for a subway train during the “No Pants Subway Ride” in Prague January 11, 2015. (Photo by David W. Cerny/Reuters)

A passenger not wearing pants reads a book as he stands in a subway train during the “No Pants Subway Ride” in Prague January 11, 2015. (Photo by David W. Cerny/Reuters)

Passengers not wearing pants stand in a subway train during the “No Pants Subway Ride” in Prague January 11, 2015. (Photo by David W. Cerny/Reuters)

Passengers not wearing pants sit on a subway train during the “No Pants Subway Ride” in Prague January 11, 2015. (Photo by David W. Cerny/Reuters)