The Sadist (1963)

  Three school teachers on their way to Los Angeles for a Dodgers game get car trouble and stop at a wrecking yard. A gun-wielding teenage maniac and his non-speaking girlfriend appear and start terrorizing them, killing one of them and forcing the other two to cooperate. A twisted game of death ensues...
  James Landis directs what is believed to be the first film based on an actual serial killer's life. Following the deeds Charles Starkweather and Caril Fugate (see Oliver Stone's Natural Born Killers), the film creates a heavy thriller atmosphere filled with tense dialogues and close-to-cheesy lines that guarantee an enjoyable but shocking 90 minutes.Vilmos Zsigmond put his dirty little hand in the film so it is easy to see why it is so unique. Make no mistake. This film may be cheap and look like your average exploitation but it has the potential to be much more than that!
  Arch Hall Jr. does surprisingly good at portraying the maniac, half-crazed teen that feels nothing when he kills and so does Marilyn Manningas his mute girlfriend who shares the same brain damage! When everyone expected Arch Hall to fail, he proved them wrong. Richard Alden, Don Russell and Helen Hovey are the three teachers that were just too unlucky. They too show great talent in showing fear and anxiety for their lives but  Helen Hovey is too much of a scream queen for my taste!
Must watch this : definitely watch this when you get the chance. This is true cinema art. Ideally, watch it on a hot, quiet July night with your girlfriend and some orange juice. Don't speak throughout the film and let it speak to you with its heaviness! Then listen to this dirty homage to this spree killer !
Trailer
http://www.imdb.com/title/tt0057465/

The worst nightmares come when I have to grade my students' test!

My parents are not around so I will drink all the sodas and kill all of you!

Oh, snap! Mother fucking lens!