Flappers' hairdos, also known as bobbed hair, were popular in the 1920s. The style was characterized by short, straight hair that was cut just below the ears and often had bangs. This hairstyle was seen as a symbol of liberation for women, as it was a departure from the traditional long hair styles of the time. The term 'BOB' is derived from the four-letter word BOBS, which is one of the solutions to the crossword puzzle.