Two zebras stand so close in Ngorongoro Crater, Tanzania. (Photo by Zhayynn James/Solent News)

Two friends take a quick selfie during the Grand National Festival at Aintree Racecourse on April 6, 2017 in Liverpool, England. (Photo by WENN)

The lead singer of one band talks to two bemused kids at a gig at the “Warzone Centre” in Belfast, Northern Ireland, 1980s. (Photo by Ricky Adam/Mediadrumworld)

Two men using an electric power saw to fell a tree circa 1940's. (Photo by Keystone View/FPG/Getty Images)

Soldiers, including two recruits who have brought some chickens, at Victoria prepare to board the train for the battle front. (Photo by Hulton Archive/Getty Images)

A US Marine leads two Viet Cong suspects in restraints during the Tet Offensive on February 20, 1967. (Photo by Bettmann Archive/Getty Images)

A retired man (L) looks toward two girls wearing miniskirts, July 13, 1969 in Nice, France. (Photo by AFP Photo)

Woman waking up with two men in her bed. (Photo by Ilbusca/Getty Images/iStockphoto)