A police officer removes a reveler from standing on a post as they guard and clear the street of revelers dressed in holiday themed costumes during SantaCon in New York Saturday, December 12, 2015. As thousands of Santa-suited merrymakers prepare to hit the city's streets and bars, organizers of the annual pub crawl say they're taking more steps than ever to deter naughty behavior. (Photo by Andres Kudacki/AP Photo)

A Mai-Mai rebel soldier shows off his guns at a checkpoint near the Mugunga refugee camp in Zaire; 1996. (Photo by Carol Guzy/The Washington Post)

A woman cartwheels through the Coachella Valley Music and Arts Festival in Indio, California April 10, 2015. (Photo by Lucy Nicholson/Reuters)

A young boy rests by empty USAID vegetable oil tins in the Dagahaley refugee camp which makes up part of the giant Dadaab refugee settlement on July 19, 2011 in Dadaab, Kenya. The refugee camp at Dadaab, located close to the Kenyan border with Somalia, was originally designed in the early 1990s to accommodate 90,000 people but the UN estimates over 4 times as many reside there. The ongoing civil war in Somalia and the worst drought to affect the Horn of Africa in six decades has resulted in an estimated 12 million people whose lives are threatened. (Photo by Oli Scarff/Getty Images)

Actress Bella Thorne attends the Teen Choice Awards 2015 at the USC Galen Center on August 16, 2015 in Los Angeles, California. (Photo by Steve Granitz/WireImage)

A visitor kneels down nex to an iCub robot made by the Italian Institute of Technology at the scientists congress IROS 2015 in Hamburg, Germany October 2, 2015. The robot congress is organized by TAMS group (Technical Aspects of Multimodal Systems) of Hamburg's university. (Photo by Fabian Bimmer/Reuters)

The CBRE Urban Photographer of the Year competition – now in its ninth year – encourages professional and amateur photographers to capture cities at work. Here: Dog Walker – 15:00. The competition allows photographers to enter up to 24 images, one representing each hour of the day. (Photo by Johanna Siegmann)

A surfer runs down the beach past hundreds of Barbie dolls comprising the sculpture 'Wave 2' by West Australian artist Annette Thas on Tamarama Beach during the 19th annual Sculptures by the Sea exhibition in Sydney, October 23, 2015. Sydney's coastal walk between Bondi and Tamarama has been transformed into a temporary sculpture park featuring over 100 sculptures from Australian and international artists, billed as the largest free sculpture exhibition in the world. (Photo by Jason Reed/Reuters)