A woman takes part in a four-minute flash mob pillow fight at the Old Town Square in Prague, Czech Republic, December 22, 2016. (Photo by David W. Cerny/Reuters)

Swimmers in fancy costume take part in the New Year's Day swim at Saundersfoot in Wales, Britain, January 1, 2017. (Photo by Rebecca Naden/Reuters)

Drivers take part in a demolition derby organised by the Malta Motor Sports Association to raise funds for charity in Ta' Qali, outside Valletta, Malta, January 8, 2017. (Photo by Darrin Zammit Lupi/Reuters)

Girls suffering from dwarfism take part in the disability pride parade in New York, July 12, 2015. The parade grand marshal was former U.S. Sen. Tom Harkin, the Iowa Democrat who 25 years ago sponsored the Americans With Disabilities Act. (Photo by Eduardo Munoz/Reuters)

Air National Guard takes to the skies over Puget Sound during Seafair 2015 on Thurs., July 30, 2015 in Seattle, Wash. (Photo by Matt Mills McKnight/AP Images for John Klatt Airshows, Inc.)

A woman takes a dip in a font on the eve of the Orthodox Epiphany in central Moscow, Russia, January 18, 2016. Orthodox believers mark Epiphany on January 19 by immersing themselves in icy waters regardless of the weather. (Photo by Sergei Karpukhin/Reuters)

Mask dancers take part in a parade during the the International Festival of Masquerade Games “Surva” in the town of Pernik, some 30 km from Sofia, Bulgaria, January 31, 2016. (Photo by Vassil Donev/EPA)

A performer takes part in a street parade as part of the opening ceremony of the Ibero-American Theater Festival in Bogota, Colombia, March 12, 2016. (Photo by John Vizcaino/Reuters)