A man wearing a Pikachu hat, a character from Pokemon, plays Pokemon Go during a gathering to celebrate “Pokemon Day” in Mexico City, Mexico August 21, 2016. (Photo by Carlos Jasso/Reuters)

Young people fight for fun with their pillows, during the International Pillow Fight Day at the Place des Grottes, in Geneva, Switzerland, Saturday, April 4, 2015. The annual International Pillow Fight Day takes place in hundreds of cities around the world. (Photo by Salvatore Di Nolfi/AP Photo/Keystone)

A Nepalese devotee bows in front of a cow during the 'Gai Puja', also known as the Cow Worship Day, as part of the Tihar festival in Kathmandu, Nepal, 11 November 2015. The Tihar festival is the second most important event for Nepalese Hindus. During the celebrations people worship cows, considered the incarnation of Lord Laxmi, the god of wealth. (Photo by Narendra Shrestha/EPA)

People stand with sheep for sacrifice outside a church during St. George's Day celebration in the village of Ikalto, Georgia, November 23, 2015. Georgia marks on Monday one of its most popular religious and public holidays. (Photo by David Mdzinarishvili/Reuters)

History enthusiasts of French association “Arquebusiers de l'Est”, dressed as soldiers of 3rd regiment of Zouave, attend an Armistice Day ceremony to commemorate the end of World War One at Epernay, eastern France, November 11, 2014. More than a hundred volunteers from France, Romania, England, Belgium, Russia and Italy took part in the parade. The year 2014 marks the centennial commemoration for the soldiers who fought in the First World War (WWI). (Photo by Charles Platiau/Reuters)

Four men dressed as zombies participate in a Zombie Walk procession in the streets of Paris October 12, 2013. (Photo by Benoit Tessier/Reuters)

Elephants enjoy various kinds of fruits and vegetables during an all-you-can-eat elephant buffet held to mark the National Elephant Day at the ancient historical city of Ayutthaya, Thailand, 13 March 2014. The annual National Thai Elephant Day is held on 13 March to celebrate and drawing public attention for more concerted effort to save the species and protect its habitat. Thailand sees a severe decline with less than 3,000 wild elephants left in the kingdom. (Photo by Rungroj Yongrit/EPA)

World War II veterans danced during Victory Day celebrations in Minsk, Belarus, Thursday, May 9, 2013. Belarus and other former Soviet countries celebrated the 1945 victory over Nazi Germany on Thursday. (Photo by Viktor Drachev/AFP Photo)