In this July 25, 2015 photo, youth eat a cooked pig's head as they wait for the start of carnival in Santiago, Cuba. (Photo by Ramon Espinosa/AP Photo)

A Syrian boy looks through a gate as others wait to cross into Syria at Oncupinar border crossing in the southeastern city of Kilis, Turkey February 11, 2016.. (Photo by Osman Orsal/Reuters)

Dogs, Pretty, Llilly, and Rocky wait for their turn to be examined by veterinarians during a community campaign for the sterilisation and deworming of dogs and cats in Havana, Cuba February 25, 2016. (Photo by Reuters/Stringer)

A man sits waiting for a train on the London Underground in 1890, when the platform floors were still made from wooden floorboards. (Photo by Hi-Story/Alamy Stock Photo)

A beauty contestant waits backstage during the final of the annual Miss Tiffany's Universe 2016 transvestite contest in the beach resort town of Pattaya, Thailand, May 13, 2016. (Photo by Athit Perawongmetha/Reuters)

Aspiring models wait for their turn to be judged during auditions for the upcoming Lakme Fashion Week in Mumbai, India, June 30, 2016. (Photo by Shailesh Andrade/Reuters)

Men selling sheep wait for customers at a local livestock market, ahead of the Eid al-Adha festival, in Lagos, Nigeria September 11, 2016. (Photo by Akintunde Akinleye/Reuters)

Angel Paz, dressed as a calavera, waits with family for the start of the Gran Procession of the Catrinas, to mark the upcoming Day of the Dead holiday, in Mexico City, Sunday, October 23 2016. (Photo by Anita Baca/AP Photo)