Frankie (Frankie Avalon) and Dolores (Annette Funicello) are looking forward to a summer alone in a beach house, but when they arrive, Frankie is dismayed to find that Dolores invited all their friends to stay in the house, meaning they won't get any privacy. To get revenge, Frankie romances Hungarian waitress Ava (Eva Six). Dolores responds by dating Robert O. Sutwell (Bob Cummings), a professor of developmental biology and anthropology, who is researching the mating rituals of surf-dwellers. When Eric Von Zipper (Harvey Lembeck), the leader of an outlaw biker gang, sexually harasses Dolores, Sutwell fights him off. Von Zipper plots to defeat Sutwell.
Beach Party contains examples of:
- Adults Are Useless: Aside from Marianne, who seems savvy enough to leave the teens to their fun, the adults like Robert and the Rat Pack are portrayed as bumbling and incompetent.
- Age-Gap Romance:
- Robert Sutwell is somewhere between forty and fifty, and has Ship Tease with Dolores, who's between seventeen and nineteen.
- Frankie likewise is seventeen-nineteen, and he pursues Ava, who's in her mid-twenties.
- All Bikers Are Hells Angels: Parodied with Eric Von Zipper and his Malibu Rat Pack, who are anything but Badass Bikers.
- Awesomeness by Analysis: Sutwell does some calculations in the sand involving things like water pressure, allowing him to surf successfully with little practice.
- Beach Bury: Ken (John Ashley) buries Deadhead (Jody McCrea) under a sand body that's meant to look like Ava, with huge breasts and seaweed hair. When the real Ava shows up, Deadhead jumps up in embarrassment.
- Betty and Veronica:
- Biting-the-Hand Humor: Marianne mockingly says of Robert's thesis "American International will snap it up in a minute." The film is produced by American International Pictures.
- Bridal Carry: Frankie carries Dolores into the beach house, only to trip on one of the guests. Later, Sutwell carries her out of his plane after she gets motion sickness.
- The Cameo: Big Daddy is revealed to be played by Vincent Price, who then nods to his role in another AIP film:
- Carry the One: Sutwell's first attempts at surfing make up a Failure Montage of him falling off the board before he realizes he forgot to carry the two.
- Distracted by the Sexy: Rhonda stretches in a bikini to distract male surfers so they wipe out.
- Embarrassing Middle Name: Sutwell is embarrassed of his middle name, Orville.
- The End: "The End Almost" appears before the end credits.
- Europeans Are Kinky: The vampy Ms. Fanservice Ava probably wouldn't be as vampy if she weren't played by sexy Hungarian Eva Six.
- Fanservice Extra: Every beach scene is full of attractive people of both sexes in skimpy outfits.
- Goldfish Poop Gang: The Rat Pack are so incompetent, even the dorky scientist is able to one-up them.
- Hypercompetent Sidekick: Marianne is Genre Savvy and seems far wiser than Robert.
- Jerkass Has a Point: The one part in the film where Frankie kind of has a point is that Dolores had led him to believe they'd be going on a vacation just the two of them - and she invited all their friends behind his back.
- Let's Wait a While: Dolores invites their friends because she doesn't trust herself not to give in if she's alone with Frankie. She wants him to see her as a wife, not just another girl, and doesn't think that will happen unless she saves herself.
- The Makeover: Sutwell shaves off his beard towards the end of the second act.
- The Man in the Mirror Talks Back: Dolores sings a duet with her reflection.
- Mumbling Brando: Eric Von Zipper is an obvious parody of Marlon Brando's performance in The Wild One.
- Nice Hat: Sutwell wears a straw hat with a house, a palm tree, and some doll villagers on it to a campfire gathering. Unfortunately, one of the teenagers sets the hat on fire.
- Operation: Jealousy: Frankie and Dolores spend most of the movie attempting this.
- Pie in the Face: During the surfers' brawl with the bikers, Ava calls Von Zipper "my hero." Dolores says "That does it" and pies her. The brawl quickly devolves into a pie fight.
- Pocket Protector: Von Zipper punches Sutwell in the stomach, but only succeeds in breaking the tape recorder he's wearing under his shirt.
- Pressure Point: Sutwell can hold his own in fights with the bikers because he knows the Himalayan Time-Suspension Technique, which involves pressing the victim's temple a certain way with his finger, causing them to be frozen in place for hours.
- Regional Riff: The Oriental riff plays while Sutwell shows Dolores the kimono he got from the Tokyo Fire Department.
- Rule-Abiding Rebel: The teens party and surf, but don't drink or do drugs. While sex is implied, Dolores seems to want Frankie to marry her. The Arc Words of the beach movies would be known as "Good Clean Fun". Especially egregious, since it was the mid 1960s!
- Running Gag: Big Daddy's club has several people meditating who are always seen in the Lotus position, and don't seem to move - regardless of what happens in the story.
- Shoehorned First Letter: Cappy (Morey Amsterdam) recites an acrostic for Big Daddy, the mascot of his club: Dallas, Ah, DNicholas, D-Day, and Y Not.
- Smart People Wear Glasses: Invoked by Sutwell. When he first became a professor, he was so much younger than the others that he got laughed at by his students. On the advice of another professor, he grew a beard and started wearing glasses, which made people take him more seriously.
- Third-Person Person: Von Zipper tends to talk this way.Von Zipper: Eric Von Zipper likes you.
Dolores: Who's that?
Von Zipper: Me!