Students training to be flight attendants hold books on their heads, chopsticks in their mouths, and papers in between their knees, as they take part in a standing posture practice at a vocational school in Shijiazhuang, Hebei province, China May 4, 2017. (Photo by Reuters/Stringer)

Iranian women perform as they train Far East Fighting Arts to be able to defend themselves, at the Jughin castle which is located 40 km's far from Tehran, Iran on June 5, 2017. (Photo by Fatemeh Bahrami/Anadolu Agency/Getty Images)

A South China Tiger cub meets public at Guangzhou Zoo on June 22, 2017 in Guangzhou, Guangdong Province of China. Guangzhou Zoo boasts of the successful breeding of South China Tiger cub after 15 years. (Photo by VCG/VCG via Getty Images)

A robot is seen on Mount Etna, Italy on July 4, 2017. Mount Etna, in Sicily, is a test bed for the approximately three-foot high, four-wheeled machine ahead of a future mission to the moon. It is being conducted by the German Aerospace Centre, the agency which runs Germany's space programme. (Photo by Antonio Parrinello/Reuters)

A grey whale greets tourists in boat in, Baja California, Mexico, March 2017. A pair of newly born grey whale calves intrigued by visiting tourists eagerly swim over to the group to get a closer look. Urged on by their mother, the small calves confidently went up to the tour group who were visiting San Ignacio Lagoon in Baja California, Mexico. This adorable moment was captured by zoologist and wildlife photographer, Mark Carwardine on his visit to the area in March 2017. (Photo by Mark Carwardine/Barcroft Images)

Kourtney Roy makes eerie self-portraits in desolate yet dramatic locations – with wigs and wardrobe straight out of 1950s melodrama. In these shots, from her “Enter as Fiction – California” series, she plays characters caught in desolate, often abandoned settings. (Photo by Kourtney Roy/Galerie Catherine et André Hug/The Guardian)

Model Kendall Jenner poses on the red carpet as she arrives for the screening of the film “Mal de pierres” (From the Land of the Moon) in competition at the 69th Cannes Film Festival in Cannes, France, May 15, 2016. (Photo by Yves Herman/Reuters)

The Mile O' Mud is a 7/8-mile oval track with a 1/8-mile diagonal lane slashed through the center. The racing lanes are approximately 60 feet wide. On average, the muddy water is four to six feet deep, with three strategically placed holes. The largest hole, located in front of the grandstand, is the treacherous “Sippy Hole”, named for the legendary driver “Mississippi” Milton Morris, Swamp Buggy King 1955, who repeatedly got stuck in it. (Photo by Malcolm Lightner)