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In the film, Baby Button-Eyes went on a murderous rampage where she killed everyone she encountered, including Lenny Leonard's gardener character. She also induced a little girl to kill her mother, evidently by revealing her origins: Specifically, that her Button Eyes had come from the trousers of a psychotic killer.
At one point, it was thought that Baby Button-Eyes was dead, but she rose up and killed yet another person, which prompted moviegoer Homer Simpson to casually remark, "Well, what do you know? It's unkillable!"
 Behind the Laughter