Costumed participants are seen during an Irish tradition of Hunting of the Wren festival held every St. Stephen's Day in Dingle, Ireland, December 26, 2016. Wren Day, also known as Wren's Day, Day of the Wren, or Hunt the Wren Day is celebrated on 26 December, St. Stephen's Day. The tradition consists of “hunting” a fake wren and putting it on top a decorated pole. (Photo by Clodagh Kilcoyne/Reuters)

Children play with weapons during Children's Day celebration at a military facility in Bangkok, Thailand January 14, 2017. (Photo by Jorge Silva/Reuters)

Children of local herders gather at a reindeer camping ground, some 200 km (124 miles) northeast of Naryan-Mar, the administrative centre of Nenets Autonomous Area, far northern Russia, August 2, 2015. People, including local herders and members of their families, gathered at the site to mark Reindeer Day, a professional holiday of reindeer breeding workers, which is celebrated annually on August 2 in the region. (Photo by Sergei Karpukhin/Reuters)

“Sorpresa” the clown poses for a picture during a march commemorating Peruvian clown day in Lima Peru, Monday, May 25, 2015. Hundreds of professional clowns dressed in colorful costumes, wigs and face paint marched through the streets of Lima to celebrate Peruvian Clown Day. (Photo by Rodrigo Abd/AP Photo)

Students of JSS Dutse Alhaji participate in a cultural dance performance during celebrations to commemorate Nigeria's 55th Independence Day in Abuja, Nigeria, October 1, 2015. (Photo by Afolabi Sotunde/Reuters)

A woman dressed as “The Milkmaid” (Het Melkmeisje), after a painting by Dutch painter Johannes Vermeer, picks up tulips at the National Tulip Day on the Dam, Amsterdam, the Netherlands, 16 January 2016. The event is the official start of the international tulip season which runs until the end of April. (Photo by Evert Elzinga/EPA)

Young Japanese women dressed in colourful Kimonos take a photo of themselves as they gather for a ceremony marking the “Coming of Age Day” at the Toshimaen Amusement Park in Tokyo, Japan, 11 January 2016. The Coming of Age Day is the day to celebrate young people who turn 20 years old while the age of 20 is considered the beginning of adulthood and is the minimum legal age for voting, drinking and smoking in Japan. (Photo by Kiyoshi Ota/EPA)

A six-day-old hippopotamus is pictured next to his mother, Kara, aged 21, on September 12, 2012 at “Planet sauvage” (“Wild planet”) Zoo in Port-Saint-Pere, western France. The birth, a rare event for this species in captivity, occured on September 7, 2012 in the Zoo. (Photo by Frank Perry/AFP Photo)