From the experts:
Gidget was the surfer girl who started it all. She was the subject of six novels by Frederick Kohner, and the 1959 film in which she made her theatrical debut, starring Sandra Dee, helped make surfing a popular sport.
Today, her name feels fun, sunny and retro. Or rather, her nickname: the character's given name was Franzie, Gidget was her nom de surf, formed by combining "girl" and "midget."