‘Spanking the Monkey’

David O. Russell’s 1994 debut feature is a whimsical black comedy about incest, and it never lets up, sustaining even an ending that’s a letdown. Ray Aibelli (Jeremy Davies, pictured) is an MIT freshman who is called home from a summer internship with the Surgeon General to care for his temporarily bedridden mother while his father conveniently hits the road (Cinemax early Thursday at 4:15 a.m.).