Competitors take part in the 8th annual World Gravy Wrestling Championships at the Rose n Bowl Pub in Bacup, north west England on August 31, 2015. Contestants must participate in fancy dress and wrestle in a pool of Lancashire Gravy for 2 minutes whilst being scored for a variety of wrestling moves. (Photo by Oli Scarff/AFP Photo)

Participants climb over a wall at the “Tough Mudder” endurance event series in Arnsberg September 6, 2014. Competitors who took part in the endurance event saw themselves having to overcome various military style obstacles. (Photo by Ina Fassbender/Reuters)

People eat sushi off the body of a model at an opening event of a bar in Taiyuan, Shanxi province, August 22, 2015. (Photo by Reuters/Stringer)

A girl sticks out her tongue during snowfalls on a street in Hefei, Anhui province February 13, 2014. (Photo by Reuters/Stringer)

A member of the mainly Christian “anti-balaka” (anti-machete) militia trains in the Boeing neighbourhood of Bangui, Central African Republic, on February 24, 2014. (Photo by Fred Dufour/AFP Photo)

Competitors gather backstage as they prepare to take part in the All Ireland Irish Dancing Championships on November 2, 2016 in Belfast, Northern Ireland. The championships take place at the Waterfront Hall over the course of six days with winners qualifying for the World Irish Dancing Finals which will take place in Dublin next year. (Photo by Charles McQuillan/Getty Images)

Members of the University of Maryland women's lacrosse team react to something Trump said after posing for photographs during an event with NCAA championship teams at the White House on November 17, 2017. (Photo by Jabin Botsford/The Washington Post)

North Korean children wave to people on a Chinese tourist boat on the banks of Yalu River near the Chongsong county of North Korea, opposite the Chinese border city of Dandong, May 8, 2011. (Photo by Jacky Chen/Reuters)