Spike of Love (1994)

Jane, a biker chick/dominatrix, lures an innocent businessman back to her apartment for some kinky games. In the midst of fornication, her dumb boyfriend Donny and his religious nut brother Clem return with the severed head of their first murder victim, and who are now fearing for their lives from a vengeful gang of psychos. Donny plots to brutally murder the businessman, while Clem continues studying for his correspondence course in priesthood.