Pinup is Cheesecake or at least that's what is the most common thought. Actually, "pinup and pinup models" became uber popular in the 40's and 50's. The heyday of Advertising agencies. Pinup was a highly used method of advertising and often it contained images of scantily clad woman or men sometimes. These images would be torn from magazines or sold out right to be "pinned up" on walls.
When I create pinup I try to harken back to the styles of the 40 and 50's pinup art and weave a bit of my advertising experience and a bit of modern day design into my final image.