Fighters battle in Manhattan's Union Square during a massive pillow fight on April 2, 2011 in New York City. Over 130 cities worldwide are participating in the fourth annual International Pillow Fight Day. (Photo by Mario Tama/Getty Images)

Iraqi security forces take part in training, as they prepare to fight against militants of the Islamic State, at a training camp on the outskirts of Mosul January 10, 2015. (Photo by Azad Lashkari/Reuters)

Women wearing sunglasses pose for a group photo at a park in Beijing in 1980. (Photo by Reuters/China Daily)

Robot pianist Teo Tronico performs at the World Robot Conference (WRC) 2017 at Etrong International Exhibition & Convention Center on August 22, 2017 in Beijing, China. The World Robot Conference 2017 is held from August 23 to 27 in Beijing. (Photo by Liu Guanguan/China News Service/VCG via Getty Images)

Ethnic Miao women wearing traditional costumes take part in a parade during the traditional Lusheng (reed-pipe wind instrument) festival in Gulong, Guizhou province, China November 15, 2017. (Photo by Reuters/China Stringer Network)

A woman wearing a swim suit skis during the Naked Pig Skiing Carnival at the Yabuli Ski Resort on March 24, 2018 in Harbin of Heilongjiang Province, northeast China. (Photo by Tao Zhang/Getty Images)

Participants pose as they take part in a bodybuilding and fitness event named “China Fit”, in Beijing, China, June 15, 2016. (Photo by Reuters/Stringer)

Taiwanese and Chinese nationals suspected of telecom fraud are surrounded by China police SWAT team and Cambodia police as they were deported to China at the International Airport of Phnom Penh, June 24, 2016. Scores of Chinese police officers swarmed the tarmac at Phnom Penh International Airport on Friday as 39 suspects arrested for their involvement in an alleged telecom scam were herded onto a chartered plane bound for China – including 25 Taiwanese nationals, whose government unsuccessfully attempted to have them repatriated. (Photo by Samrang Pring/Reuters)