Flappers were a subculture of young Western women in the 1920s who wore short skirts (knee height was considered short during that period), bobbed their hair, listened to jazz, and flaunted their disdain for what was then considered acceptable behavior. Flappers were seen as brash for wearing excessive makeup, drinking alcohol, smoking cigarettes in public, driving automobiles, treating sex in a casual manner, and otherwise flouting social and sexual norms.

Source: Wikipedia