Betty Boop gets a birthday cake delivered to her in “Betty Boop’s Birthday Party” (1933). Being a Fleischer cartoon, it’s only natural the candles come to life and wish Betty a happy birthday. And they develop little rumps in the process before returning to being to inanimate objects.
Seymour Kneitel and Myron Waldman get the on-screen animation credits. Mae Questel doesn’t voice Betty in this one.