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)

Sri Lankan military personnel march during the country's 66th Independence Day celebrations in the central town of Kegalle, about 40 kms from the capital Colombo on February 4, 2014. Sri Lanka cemmemorates its independence from British rule on February 4, 1948. (Photo by Ishara S. Kodikara/AFP Photo)

A sticker is seen at the Rocky Mountain Guns and Ammo store in Parker, Colorado July 24, 2012. The killing of 12 people at a midnight screening of the new Batman movie in the Denver suburb of Aurora may spark a fresh round of soul-searching on America's relationship with guns but few predict any real change in the law. (Photo by Shannon Stapleton/Reuters)

British singer Cheryl Fernandez-Versini aka Cheryl Cole arrives for the screening of “Ma Loute” (Slack Bay) during the 69th annual Cannes Film Festival, in Cannes, France, 13 May 2016. (Photo by Sebastien Nogier/EPA)

An Indian girl smiles under a water splash at a water park as the temperatures reached 38 degree Celsius in Calcutta, eastern India, 12 June 2016. The summer or pre-monsoon season lasts from March to July in eastern India with the highest day temperatures ranging from 38 to 45 degrees Celsius. (Photo by Piyal Adhikary/EPA)

Jean-Pierre Giagnoli walks through a crowded area of vendors hawking cat related goods at CatCon LA in Los Angeles, on Sunday, June 26, 2016. (Photo by Richard Vogel/AP Photo)

The NASA Extreme Environment Mission Operations (NEEMO) 21 mission began on July 21 as an international crew of aquanauts splashed down to the undersea Aquarius Reef Base, located 62 feet below the surface of the Atlantic Ocean in the Florida Keys National Marine Sanctuary. The NEEMO 21 crew will perform research both inside and outside the habitat during a 16-day simulated space mission. During simulated spacewalks carried out underwater, they will evaluate tools and mission operation techniques that could be used in future space missions, including journeys to Mars. (Photo by Karl Shreeves/NASA)

An officer of the Afghan border police throws an assault rifle to a policeman participating in a military exercise on the outskirts of Herat, Afghanistan, Monday, September 7, 2015. Twelve female and seventy male border police personnel participated in the military exercise near the border with Iran in Herat province. (Photo by Hoshang Hashimi/AP Photo)