Alex Plunkett, left, and Sean Hart, both of Arlington, Va., join hundreds participating in the annual International Pillow Fight Day on April 5. Massive pillow fights broke out on the Mall in Washington and in cities around the world. (Photo by Marvin Joseph/The Washington Post)

A girl plays in the Eshash el-Sudan slum in the Dokki neighbourhood of Giza, south of Cairo, Egypt September 2, 2015. Residents of the slum clashed with police in late August, when about 50 ramshackle huts were destroyed and at least 20 people were injured by teargas, local media reported, as authorities attempt to clear the area and rehouse residents. The slum dwellers, some of whom have called Eshash el-Sudan home for 50 years, say there are not enough apartments built nearby to house them. The residents of the slum eke out a living by disposing of rubbish or baking bread. Schooling is too expensive for most of their children, who play with salvaged rubbish amid shacks made out of discarded wood and leather. (Photo by Amr Abdallah Dalsh/Reuters)

Photographer Brian Finke spent nearly two years traversing the friendly skies, following the life of flight attendants in the air and on the ground, from Delta and Hawaiian Air, to Hooters Air, Southwest, Air France, British Airways, Air Asia, and dozens more. His images of flight attendants waving, applying makeup and deboarding plans while smiling appear as if they were ripped from an advertisement in a glossy magazine. Here: Tiger Airways, Singapore, 2006. (Photo by Brian Finke/The Washington Post)

People in costume take photos during a Halloween event on October 31, 2015 in Lan Kwai Fong, Central District, Hong Kong. Halloween, a named taken from 'All Hallows' Even' falls on the day before All Saints' Day on November 1, a holiday when Christians remember their deceased loved ones. (Photo by Jerome Favre/Getty Images)

A woman carrying cabbage leaves on her head buys tomato at a market in Ahmedabad, India, November 9, 2015. India's villages face a sharp spike in food prices in 2016, as a second year of drought drives up the cost of ingredients such as sugar and milk, and poor transport infrastructure stops falling global prices from reaching rural areas. (Photo by Amit Dave/Reuters)

Syrian refugees sit behind barbed wire as they wait to cross into Macedonia at the Greek-Macedonian border, near the village of Idomeni, August 21, 2015. (Photo by Yannis Behrakis/Reuters)

“Only the most intrepid urban explorers cross the tattered ruins of the old Iron Curtain to endure the excessive bureaucracy, military paranoia and freezing winds of the East to hunt for the ghosts of an empire. Rebecca Litchfield is one who couldn't resist the haunting allure of the ruins of the Soviet Union”. – Yahoo News. Photo: Hungary, MAV 424 Steam Train. (Photo by Rebecca Bathory)

A street artist dances tango in Buenos Aires, Argentina, Tuesday, January 20, 2015. Tango is a partner dance that originated in the 1890's along the Rio de la Plata, the border between Uruguay and Argentina. UNESCO approved in 2009, a joint proposal by the two nations to include the dance in its Intangible Cultural Heritage List. (Photo by Rodrigo Abd/AP Photo)