Prince Philip, Duke of Edinburgh practicing his bicycle polo technique, Windsor Great Park, Berkshire, 1964. (Photo by Norman Potter/Daily Express/Hulton Archive/Getty Images)

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)

A visitor kneels on the 180-meter-high and 300 meter-long glass-bottomed suspension bridge at the Shiniuzhai National Geopark in Pingjiang county, in central China's Hunan province, 24 September 2015. (Photo by Jiao Zi/Imaginechina via AFP Photo)

Julia Marino of USA in action during the final run of the snowboard slopestyle competition at the Laax Open, in Laax, Switzerland, 17 January 2020. (Photo by Gian Ehrenzeller/EPA/EFE/Rex Features/Shutterstock)

A streaker races across the field and is caught by security during the Super Rugby match between New Zealand's Highlanders and South Africa's Sharks at Forsyth Barr Stadium in Dunedin on February 7, 2020. (Photo by Marty Melville/AFP Photo)

A public bus makes its way on a flooded road after heavy monsoon rains in Mumbai, India on August 4, 2019. India receives its monsoon rains from June to September. (Photo by Indranil Mukherjee/AFP Photo)

A woman yawns as she sits outside a hospital on a cold winter morning in Srinagar January 3, 2019. (Photo by Danish Ismail/Reuters)

A boy jumps from a swing during sunset in Valras-Plage, southern France December 29, 2014. (Photo by Yves Herman/Reuters)