A mass pillow fight in Trafalgar Square in central London on April 5, 2014 on International Pillow Fight Day. (Photo by Jane Scanlan)

In this Sunday, May 29, 2016 photo, fighters take a selfie while firing artillery during fight against Islamic State militants in Fallujah, Iraq. Iraqi forces this week pushed into the city's southern sections after securing surrounding towns and villages more than 50,000 people are believed to be trapped inside the Sunni majority city, about 65 kilometers (40 miles) west of Baghdad. (Photo by Anmar Khalil/AP Photo)

A supporter of the presidential candidate for the Honduran Opposition Alliance Against the Dictatorship for the past election, Salvador Nasralla, lies on the street in front of police officers during a demonstration against the contested re-election of President Juan Orlando Hernandez, in Tegucigalpa, Honduras on January 21, 2018. (Photo by Orlando Sierra/AFP Photo)

A dog walks past a mural by street artist Alex Martinez outside a shop which sells bags at Psiri area, central Athens, on Thursday, January 25, 2018. (Photo by Petros Giannakouris/AP Photo)

A demonstrator confronts riot police during a rally in defense of the nationalization of lithium reserves in the country, in Santiago, Chile on January 29, 2018. (Photo by Pablo Sanhueza/Reuters)

The rising sun illuminates the sky above the spires of a church in Vienna, Austria, November 17, 2015. (Photo by Heinz-Peter Bader/Reuters)

Racegoers in fashionable hats attend Ladies Day at Cheltenham Festival on March 15, 2017 in Cheltenham, England. (Photo by David Davies/PA Wire)

A motorcyclist ferries a pillion rider sitting on goods in Phnom Penh on June 6, 2017. (Photo by Tang Chhin Sothy/AFP Photo)