Two friends take a quick selfie during the Grand National Festival at Aintree Racecourse on April 6, 2017 in Liverpool, England. (Photo by WENN)

People dressed as ancient Roman reflect on a helmet during a parade to mark the anniversary of the foundation of Rome in 753 BC, on April 23, 2017 in Rome, Italy. (Photo by Alberto Pizzoli/AFP Photo)

Men slide in the mud during the Boryeong Mud Festival at Daecheon Beach in Boryeong, South Korea, Saturday, July 22, 2017. The 20th annual mud festival features mud wrestling and mud sliding. (Photo by Ahn Young-joon/AP Photo)

Clouds gather as walkers pause atop a ridge in Mountain View, California January 7, 2016. (Photo by Noah Berger/Reuters)

Pro-government fighters stand next to a tank destroyed during recent fighting in Yemen's southwestern city of Taiz March 14, 2016. (Photo by Anees Mahyoub/Reuters)

A woman dressed as a character from the computer game “World of Warcraft” stands in a forest near the village of Sosnova, Czech Republic, April 30, 2016. (Photo by David W. Cerny/Reuters)

People play on a beach along the Arabian Sea on a hot summer day in Mumbai, India, April 29, 2016. (Photo by Danish Siddiqui/Reuters)

People participate in a Zombie Walk in Sao Paulo, Brazil, November 2, 2016. (Photo by Nacho Doce/Reuters)