Women in costumes walk as they participate in Halloween celebrations in the downtown of Seoul, South Korea, October 31, 2015. (Photo by Kim Hong-Ji/Reuters)

A participant races in the Brompton World Championship in Bern, Switzerland October 21, 2018. (Photo by Stefan Wermuth/Reuters)

A woman dressed up as a zombie participates in a zombie walk in Stockholm, Sweden on August 19, 2017. (Photo by Jonathan Nackstrand/AFP Photo)

Women participate during the Mr. Olympia Amateur South America bodybuilding competition in Medellin, Colombia, February 19, 2017. (Photo by Fredy Builes/Reuters)

Brides-to-be participate in the “Running of the Brides” race in a park in Bangkok, Thailand March 25, 2017. (Photo by Athit Perawongmetha/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)

A competitor participates in the Tough Mudder challenge near Henley-on-Thames in southern England May 2, 2015. (Photo by Eddie Keogh/Reuters)

A participant smiles at the annual Christopher Street Day parade on Kurfuerstendamm in Berlin, Germany, June 27, 2015. (Photo by Fabrizio Bensch/Reuters)