Young man making the O.K. sign. (Photo by George Marks/Retrofile/Getty Images). Circa 1950s

Musician Kirk Hammett of Metallica performs onstage during The Big 4 held at the Empire Polo Club on April 23, 2011 in Indio, California.

A zebra walks through the recently flooded Safari Park located at Safari World November 2, 2011 in Bangkok, Thailand. (Photo by Paula Bronstein /Getty Images)

A competitor shows her nails during the Tokyo Nail Expo 2009 at Tokyo Big Sight on November 30, 2009 in Tokyo, Japan. (Photo by Junko Kimura/Getty Images)

Travellers stop to take a second glance at a model of a giant lady with her head stuck in a photo booth being exhibited in Victoria train station on September 21, 2007 in London, England. (Photo by Cate Gillon/Getty Images)

British prime minister Winston Churchill (1874–1965) stops to pet a cat at Liverpool Street Station, 24th May 1952. (Photo by Keystone/Hulton Archive/Getty Images)

A mahout (elephant driver) walks a baby elephant across the city streets at night September 27, 2008 in Bangkok, Thailand. (Photo Paula Bronstein/Getty Images)

Professional dog walker Jon Lovette of Jonny Walkers walks with dogs at Crissy Field on October 19, 2011 in San Francisco, California.