Bimbo's Initiation (1931)

Released July 24th, 1931, Bimbo's Initiation is an early animated short film from the Talkartoons series of cartoons, which starred Betty's love interest Bimbo the dog, before Betty had her own cartoon. The cartoon features Bimbo finding himself being menaced by an occult secret society, putting him through a series of frightening fun-house gag situations, occasionally breaking off to ask Bimbo in song: "wanna be a member? wanna be a member?" to which Bimbo continually replies with a firm rejection, that is until Betty appears and her dancing hips seem to hold more sway.

These were some enthralling times in the pre-code era, with one of the weirdest and darkest Fleischer cartoons I can recall (next to Minnie the Moocher), and Betty, although still a dog anthropomorph at this time in her career, is risque as ever. The 3D environments giving dynamic to Bimbo's nightmarish journey through the fun-house are amazing even for today. This is one of my favorites. Be sure to watch for a clever Mickey Mouse cameo.

Although Betty is the secondary character here, she makes quite an impression. Towards the end when she starts to dance for Bimbo, I couldn't help sensing some sort of proto-twerking, or at the very least an early instance of booty-shaking for seductive and/or titillation purposes (this wasn't a thing until the '90s, people).