Three On A Meathook (1972)

aka: 3 On A Meathook!

Four girls go on a romping weekend at a lake and have car problems on the way home. A nice local boy (James Pickett) takes them back to his farm, where he lives with his father (Charles Kissinger). Something ghastly happens, but the father helps his son as he has in the past. When the boy meets a girl and begins falling in love, the father worries about a repeat performance. Features some cool gore effects created by Pat Patterson. Also stars Sherry Steiner.