Betty's development was still incomplete, however. Max Fleischer's brother, Dave, further altered the character, making her sexier and more feminine. Betty's famous personality finally came into play in the 1932 short, Minnie the Moocher, to which Cab Calloway and his orchestra lent their talents. In the film, Betty runs away from her over-bearing parents only to get lost with costar Bimbo in a cave haunted by a walrus (rotoscoped from Calloway). The ghost's scary musical number impels Betty to flee back to the safety of home. The portrayal of Betty's parents as seemingly being Orthodox Jews has led many to assume that Betty herself was intended as an overtly Jewish character . However later episodes, such as the 1936 short "Be Human," introduced Betty's Grandpa, who was portrayed very much as an 'old timer' in the style of such characters from Wild West films.
Betty Boop is noteworthy for being the first cartoon character to fully represent a sexual woman. Other female characters of the same period showed their panties regularly, like Minnie Mouse, but didn't have a full caricature of a woman's form. Betty Boop, however, reveled in her sexuality. She wore short dresses and a garter belt. Her breasts were prominent, and she showed her cleavage. In her cartoons, other characters try to sneak peeks at her while she's changing. In Betty Boop's Bamboo Isle, she does the hula wearing only a lei and a grass skirt, a bit she repeated in her cameo appearance in the first Popeye cartoon.
Nevertheless, the animators made sure to keep the character "pure" and girl-like (officially, she was only 16 years old). As Betty tells Koko the Clown in the film Boop-Oop-A-Doop after being threatened by a salacious ringmaster, "He couldn't take my boop-oop-a-doop away!"
Her cartoons also stood out from the competition due to their upbeat jazz soundtracks. In addition to three cartoons with soundtracks by Cab Calloway, guest bands for Betty Boop cartoons included the bands of Louis Armstrong, Rudy Vallee, and Don Redman. Ethel Merman, Irene Bordoni and Reis and Dunn also appeared in a few shorts as guest performers.
The adult sensibilities of Betty's cartoons made her a hit, and a wave of merchandising soon swept the world. Meanwhile, Helen Kane, who had inspired the character in 1930, sued the Fleischer studio in 1934 for allegedly stealing her trademark look, dancing and singing style, and catchphrase. Kane lost the suit (and her boop-oop-a-doop) when the Fleischers proved that the phrase had been used by other performers before Kane.
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