A vendor sells chili peppers at his stall at a market in Bangkok, Thailand March 31, 2016. (Photo by Jorge Silva/Reuters)

Revellers take part in a zombie parade to celebrate Halloween in Vina del Mar, October 31, 2015. (Photo by Rodrigo Garrido/Reuters)

A group of youngsters dressed as ghouls and zombies for Halloween parade in downtown Lisbon, Portugal, Friday, October 31, 2014. (Photo by Francisco Seco/AP Photo)

Revelers march during the Greenwich Village Halloween Parade, Tuesday, October 31, 2017, in New York. (Photo by Andres Kudacki/AP Photo)

People wearing costumes walk during Halloween in Sierra Madre, California, U.S., October 31, 2017. (Photo by Mario Anzuoni/Reuters)

Security personnel patrol around West Lake in Hangzhou, Zhejiang Province, China, August 31, 2016. (Photo by Reuters/Stringer)

Bonobo apes, primates unique to Congo and humankind's closest relative, groom one another at a sanctuary just outside the capital Kinshasa, Congo on October 31, 2006. (Photo by Finbarr O'Reilly/Reuters)

A Tibetan woman with horses in a remote area of the Yushu Autonomous Prefecture of the Tibetan Plateau on May 31, 2016. (Photo by Giulia Marchi/The Washington Post)