A line of soldiers firing handguns during a training session, circa 1920. (Photo by Keystone). P.S. All pictures are presented in high resolution.

A Saudi soldier fires a mortar towards Houthi movement position, at the Saudi border with Yemen April 21, 2015. (Photo by Reuters/Stringer)

Three Chinese soldiers at the time of a civil war in China. (Photo by General Photographic Agency/Getty Images). 1922

Office sеx. (Photo by Orange-Melody/Getty Images)

Actresses Vonnie Lui (R) and Yukiku Suou (L) attend the “3D s*x And Zen: Extreme Ecstacy” photocall at the Majestic Beach Pier during the 64th Cannes Film Festival on May 14, 2011 in Cannes, France. (Photo by Michael Buckner/Getty Images)

Members of the New People's Army (NPA) female guerrillas perform a cultural show during the release of a Philippines army soldier in Sugbongcogon town, Misamis Oriental, southern Philippines, November 20, 2015. NPA spokesperson Allan Juanito warned that they will seize more soldiers to exchange them with the government as "Prisoners of war". (Photo by Froilan Gallardo/Reuters)

A female Syrian soldier from the Republican Guard commando battalion drives a tank during clashes with rebels in the restive Jobar area, in eastern Damascus, on March 25, 2015. The female battalion, which was created nearly a year ago, consists of 800 female soldiers who are positioned in the suburbs of the Syrian capital where they monitor and secure the frontlines with snipers, rockets and machine guns. (Photo by Joseph Eid/AFP Photo)

A devotee of the Chinese Jui Tui Shrine has his face pierced with metal rods during a street procession during the annual Vegetarian Festival in the southern Thai town of Phuket on October 19, 2015. During the festival, which begins on the first evening of the ninth lunar month and lasts nine days, religious devotees slash themselves with swords, pierce their cheeks with sharp objects and commit other painful acts to purify themselves, taking on the sins of the community. (Photo by Nicolas Asfouri/AFP Photo)