The word pin-up or pinup was probably invented by Hartzell Spence during World War II. He edited Yank, a magazine for American troops which featured cartoons such as "Sad Sack," which Spence commissioned from an Army sergeant, as well as photographs of scantily-clad movie stars of the time, such as Rita Hayworth, Betty Grable and Hedy Lamarr.
'When Spence was designing the magazine, he said "We've got to have a pinup," Yank's cartoon editor, Ralph Stein, remembers. "None of us had ever heard the term. I think Hartzell might have invented it." The Oxford English Dictionary agrees. Spence died May 9 in Connecticut
at age 93.'
Source: Randy Cassingham's This Is True
e-mail newsletter, thisistrue.com, 20 May 2001.