Serial Mom

Serial Mom is a 1994 American black comedy thriller film written and directed by John Waters, starring Kathleen Turner as the title character, Sam Waterston as her husband, and Ricki Lake and Matthew Lillard as her children. Patty Hearst, Suzanne Somers, Joan Rivers, Traci Lords, and Brigid Berlin make cameo appearances in the film.

During breakfast, Detectives Pike and Gracey arrive to question the family about the vulgar harassment of their neighbor, Dottie Hinkle. After the police and her family leave, Beverly disguises her voice to make obscene phone calls to Dottie, because Dottie stole a parking space from Beverly. Later that day, Mr. Stubbins, Chips math teacher, becomes Beverlys first known murder victim after he criticizes Chips interests and questions the boys mental health and family life, as well as berating her parenting Beverly runs him over with her car, and is witnessed by Luann Hodges, a young woman smoking marijuana nearby. The next day, Misty is upset when Carl Pageant stands her up for a date. Beverly spots Carl with another girl at a swap meet and murders him in the bathroom with a fireplace poker.Eugene discovers that Beverly has hidden a collection of serial killer memorabilia beneath their mattress. That evening at dinner, Chip comments that his friend Scotty thinks that she is the killer. Beverly immediately leaves in her car, prompting the family to rush to Scottys house for fear that Beverly plans to kill him however, Beverly has actually gone to kill Eugenes patient Ralph Sterners wife, Betty, who called Eugene away to treat her husbands chronic toothache on a Saturday. She stabs Betty with scissors borrowed from Rosemary, and causes an air conditioner to fall on Ralph, who caught her killing his wife. Meanwhile, the rest of the family arrive at Scottys house only to find him in his room masturbating to an old porn video. ........

Source: Wikipedia