Traditionally, most pin-up girl designs are commercial-looking and somewhat mass-produced. A the time, the Pop Art movement was underway and women like Marilyn Monroe were famous for their sexuality. The pin-up girls are poised in seductive, alluring, or coy positions. They are usually scantily clad, often showing their mid-drifts, legs, and cleavage. Backs, shoulders, and butts were also featured. Sometimes the women were comical and funny, with humorous expressions on their faces, while other times they were innocent and sweet looking, with wide-eyes and a trusting expression.
This is what I call the style "up and down" simply because the design is the girl who just turned many times in high heels or their toes, their hindquarters before and head high. These work great for the forearms and calves.
