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)

A clown performs next to the Monument to the Revolution as he takes part in the Latin American Clown Convention in Mexico City, Mexico, October 21, 2015. The convention will be held from October 19 to 22 in Mexico City. (Photo by Henry Romero/Reuters)

A child dressed as a cat takes part in the Children's Halloween day parade at Washington Square Park in the Manhattan borough of New York October 31, 2015. (Photo by Carlo Allegri/Reuters)

A dog dressed in a costume takes part in the Pet's Halloween Day parade at El Olivar Park in San Isidro, Lima, October 31, 2015. (Photo by Mariana Bazo/Reuters)

Palestinian girls take part in a ballet dancing course, run by the Al-Qattan Center for Children, in Gaza City November 25, 2015. (Photo by Suhaib Salem/Reuters)

People take part in the "Bison Race" winter extreme run competition in Zhodino, Belarus, December 5, 2015. (Photo by Vasily Fedosenko/Reuters)