Drive-In Massacre

You'll pay to get in, and pray to get out.

Drive In Massacre is a Slasher Film released in 1977.

In a small rural California town, a dingy local drive-in suddenly makes the front page when a teenage couple is brutally butchered there one summer night, the killer's weapon of choice appearing to be a sword, of all things. Put in charge of finding the maniac responsible for this atrocious crime are Detectives Mike Leary and John Koch, who quickly narrow the suspect pool down to three persons of interest:

Austin Johnson, the assholish and constantly complaining loudmouth manager of the drive-in, left in charge of almost everything while the owner is away on vacation in Hawaii.
Charlie "Germy" Garmey, the dim but kindhearted janitor and guard who, like Austin, used to be employed as a sword swallower and knife-thrower by the carnival that existed before the drive-in.
Orville Ingleson, a local truck driver and pervert who spends his nights cruising around the drive-in, peeping on girls and, if possible, couples about to get it on.

As the detectives look into each of these oddballs, another double murder with the same MO (a lone couple mutilated with a sword) is committed at the drive-in the very next night, causing the police force to realize they are not just looking for a random murderer, but a vicious serial killer, one whose already short cooling-off period seems to be getting smaller and smaller. With no real clues or leads, and with the prime suspects all in possession of reasonable alibis, the case turns into a desperate struggle to stop the escalating killer before they commit an all-out bloodbath.

Having seemingly fallen into public domain, the film (which has not been terribly well received, having only a few defenders) is available in a number of those crappy bargain bin horror collections, and can also be viewed for free on websites such as YouTube.

An In Name Only, comedy horror remake was announced in 2011.

Attention viewers, this is the manager speaking over the PA system, informing you that the film is about to start, and stars the following tropes:

Abandoned Warehouse: The mental patient takes his daughter to one.
All There in the Script: Kathy's name is only used in the credits.
Asshole Victim: Austin.
Auto Erotica
Ax Crazy: The killer, and the mental patient.
The Bad Guy Wins/Downer Ending: The killer (who is never identified, or even glimpsed) gets away, and commits a swath of murders across the US, a different drive-in in each state.
Bald of Evil: Austin.
Beard of Evil: Austin.
Blood From the Mouth: Featured prominently in the second death.
California
Chase Scene: Orville takes off when some potentially incriminating evidence (a blood-covered cloth) is found in his car. Turns out it was just from a dog he had hit.
Cool Sword
Creator Cameo: Co-writer George Flower plays the Red Herring escaped mental patient who shows up during the last third of the film.
Credits Gag: The effects were apparently done by the so-called Duke of Disguise.
Crusty Caretaker: Germy.
A Date with Rosie Palms: "I didn't kill anybody! Look, I didn't do that! I just wanted to beat my meat!"
Death by Materialism: Austin refuses to close the drive-in due to the surprisingly high amount of revenue coming in.
Death by Sex: Almost every victim.
Diabolus Ex Nihilo: The killer is a non-entity.
Disguised in Drag: The detectives stake out of the drive-in by disguising themselves as a couple... disturbing. Austin is the only one who fails to see through the disguise.
Drive-In Theater
Everyone Is a Suspect
Extreme Omnivore: Former carnival geek Germy.
Fan Service: About two seconds of toplessness.
Fatal Family Photo: Alan's girlfriend says she wants a baby, and Lori tells David (who mentions that he has a wife and two kids) that she's pregnant.
Fat Bastard: The mental patient.
Fat Idiot: The detectives.
The Fourth Wall Will Not Protect You: Before the credits role, a fake PA announcement informs viewers that the killer is outside and that they should not panic, because the police are on the way. Obviously, this becomes less effective when the film is watched at home.
Good Cop, Bad Cop: "Well, you wanna be the good cop, or the bad cop?"
Gorn
Gross Up Close-Up
He Who Must Not Be Seen: The killer, except on this obscure VHS cover.
Hollywood Night: Averted.
If It Bleeds, It Leads: "With headlines like those it's gonna be panic city in here any time now... yeah, I dunno why they don't have headlines that big when we win one."
Impaled with Extreme Prejudice: David and Lori's dual death.
Impromptu Tracheotomy: The second death.
Insane Equals Violent: The mental patient.
In-Series Nickname: Charlie Garmey, aka Germy.
Instant Death Bullet: The mental patient's death.
Jerkass: Austin.
Knife-Throwing Act: One of Germy and Austin's old jobs.
Lack of Empathy: Austin hates everyone and everything.
Last-Name Basis: Germy's first name, Charlie, is only mentioned twice.
Leave the Camera Running: The mental patient chasing his daughter around the Abandoned Warehouse.
Loners Are Freaks: Orville.
Machete Mayhem: The mental patient wields one, and killed at least two people with it.
Man Bites Man: The mental patient's daughter escapes his grasp by biting him.
Man Child: Germy.
The Mistress: Lori.
No Name Given: The second victim, and the mental patient and his daughter.
Noodle Incident: Whatever was in Orville's rap sheet.
Nothing Is Scarier: We don't see the condition of Austin's hacked up body.
Off with His Head: Alan and Kathy's deaths.
Paper-Thin Disguise: Orville's peeping tom attire consists of nothing but a hat. This is commented on by the detectives.
Padding: The film suffers pretty badly from it, the worst instance being a long and pointless scene where Germy attends a carnival.
Pater Familicide: The mental patient killed his wife, his sister, and intended to kill his daughter.
Peek-a-Boo Corpse: Germy's hacked up body is found in a storage room.
The Peeping Tom: Orville.
Police Are Useless: And there's apparently only about four of them.
Porn Stache: The police psychologist.
Porn Stash: Orville makes no attempt to hide his, actually pasting nude pictures onto his walls, and leaving pornos on the coffee table.
The Profiler: The police psychologist.
Public Domain Feature Films
Real Life Relative: A father and daughter are played by... a father and daughter.
Serial Killer
The Seventies
Seventies Hair
Shadow Discretion Shot: Austin's death's occurs in the film booth, and the silhouette of it gets projected onto the drive-in screen.
Slashed Throat: Orville's death.
The Stakeout
Sweater Girl: Several, despite it being summer.
Unfortunate Name: Koch, which sounds suspiciously like cock.
The Un-Reveal
The Unsolved Mystery
Those Two Guys: Detectives Leary and Koch.
Title In: "On August 10 in a California Drive-In it all began..."
Too Dumb to Live: Despite the high probability of being dismembered, people keep going to the drive-in; Austin even says that business hasn't been this good since the place first opened.
Your Cheating Heart: David.
Weapon of Choice: A sword.
The Western: This appears to be the only genre of film shown at the drive-in.
Would Hurt a Child: Lori was pregnant, and the mental patient planned on killing his daughter.