In the golden age of slashers, if you did the nasty, you died. Randy from Scream — the movie that meta’ed horror — says it best: “There are certain rules that one must abide by in order to successfully survive a horror movie. Number one: You can never have sex. Sex equals death.”

A lot has changed since Wes Craven’s Ghostface debut in 1996 and since John Carpenter’s Halloween in 1978, whose analysis by Carol Clover inserted the Final Girl into our collective horror conscious (though that wasn’t really her point).

Today, sex in horror films is more complicated. In It Follows (2015), having sex both kills and saves you. In Happy Death Day (2017), Tree has intimate encounters at will, gets killed and resurrected repeatedly, and becomes a better person. In these films, sex isn’t a single act but a link in a chain of discovery.

Enter the horror subgenre: Oops I Effed Your Boyfriend, Now We’re All Gonna Die. Its most conspicuous features include:

1. a Final Girl thrill-seeker and her adventurous friends, with…
2. sex as subplot until…
3. your Bestie is bonking your Bae

One part outward bound, one part kill joint, one part monster flick, Oops I Effed delivers a simple message: it’s not just sex that equals death but infidelity — especially when caving, climbing, and diving part of the mix.

You can trust these signs to point you to your next Oops flick. Until you can’t. The Descent (2005) and Fall (2022) include them, one tipping off the other, while a third film — 47 Meters Down (2017) — nearly but frustratingly doesn’t.

More on this later, but first a look at the prototypes.

The Descent a/k/a Oops I Effed Your Husband, Now We’re Stuck in a Cave

The Descent opens with a girls’ white-water rafting trip: Sarah, Beth, sisters Sam and Rebecca, and their self-appointed pack leader, Juno. Sarah’s daughter Jessie and husband Paul arrive to pick her up, Juno glancing at them as they leave. The car ride home seems tense before a distracted Paul drives head-on into a supply van, impaling him and their daughter.

The next scenes appear as flashes. A grieving Sarah in the hospital, comforted by Beth as  Juno stands back then leaves. Death and grief separate the friends until they reunite for a “healing” adventure, planned by Juno with her “sports fanatic” Holly in tow. Unbeknownst to the group, Juno has taken them to an unmapped cave system and things quickly go sideways.

Tensions rise as exit tunnels collapse, the group becomes lost and separated, and highly capable women begin to die — all before Sarah learns that Juno had been effing Paul and that the cave is crawling with blood-thirsty beasts. The fight for survival and sanity concludes as a blood-soaked Sarah escapes to the surface with a guttural scream.

The Descent reveals its secrets delicately. At the film’s start, we’re already suspicious of Juno. By the time she stabs Beth, mistaking her for one of the cave creatures, we wonder if it’s an accident. Guilt can shake loose desires that our subconscious usually stores underground. When Sarah finds Beth, Juno’s necklace is clutched in her hand. Bearing Paul’s motto (“Live Each Day”), it reveals their infidelity.

A glance, a motto, a memento, a deception. Seeing Fall just weeks after a Descent rewatch, I remembered the plot points and discovered a subgenre.

Fall a/k/a Oops I Effed Your Husband, Now We’re Stuck on a Tower

Fall begins when Becky’s husband dies on their rock-climbing trip with friend Hunter. Hunter can’t deal, leaving Becky to drown in grief and booze. Hunter returns to revive Becky with a new adventure: climbing a 2,000-foot radio tower in the desert. Calamity ensues. An access ladder collapses, trapping the friends with no way down and one big secret. Like Juno, Hunter hadn’t kept her mitts off her best friend’s man.

Sound familiar? Oops I Effed, Now We’re All Gonna Die. The movies are so similar, it’s as if Fall was cooked up in a Ryan George Pitch Meeting:

Got a great idea for a new chick flick, action-horror.

Oh yeah?

Yeah. It’s like The Descent except people die on top of something instead of under something.

Whatcha gonna call it?

The A-scent.

Isn’t that a little obvious?

Okay, how about Fall?

The films share other features, including how they tip their secrets. In The Descent, a simple look raises our suspicions. In Fall, it’s a cropped cell phone photo and off-screen details from a wedding video. The truth is revealed when Hunter takes off her high-tops and Becky sees her tattoo — 1-4-3, Dan’s code for I-Love-You.

A glance, a motto, a memento, a deception. #bustmygriefballs

These details fed my next Oops find: 47 Meters Down. All it took to convince me was the thumbnail, the trailer, and the premise: adventurous women trapped together in “Sequences of Intense Peril” (per the MPAA).

47 Meters Down a/k/a Oops I Effed Your Boyfriend, Now We’re Stuck in a Cage

Like The Descent and Fall, 47 Meters Down starts with an adventure gone wrong: Lisa’s vacation changes course when her boyfriend dumps her because she’s no longer exciting. Instead, Lisa takes her sister Kate, who talks her into a shark cage excursion with two resort hotties and one captain hottie (the always-awesome Matthew Modine). You can guess what happens next: the cage lowers, the winch breaks, and Lisa and Kate are trapped as sharks circle.

The Oops I Effed stage was set, or so I thought:

• Female adventurers as final girls
• The protagonist’s partner dies
• Grief breaks up the band til they reunite for a healing adventure (not)

In all three movies, adventure turns intimate, claustrophobic and deadly as the women learn about themselves, one another, and what drives them. So naturally in 47 Meters Down, when the trapped sisters start sharing secrets, I imagine parallels:

Kate: I’m so sorry I got us into this [In more ways than one — like sleeping with your sister’s man!]

The other night at the hotel, what did you mean when you said that your relationship was the only thing you were good at? [Feeling guilty, hmm?]

Lisa: You’re always doing such fun stuff, Kate. Traveling around the world, doing crazy things, guys always chasing after you. I could never compete with that. I was always just your boring older sister. But my relationship with Stuart was the one thing that I had that you didn’t. [Or did she?]

I couldn’t wait to see how Kate’s crimes would be uncovered. I thought I’d found it in another detail that Fall and 47 Meters Down share: hallucinations. In a Sixth Sense-like twist, we learn that Hunter had fallen during a failed escape attempt and that Becky has been hallucinating her presence for half the film. The threat of hallucination hangs over 47 Meters, too. Surely ascending too rapidly or changing air tanks will muddle Kate’s mind and she’ll confess she schtupped Stuart.

Oops I Effed Your Boyfriend, Now We’re All Gonna Die. Except … not.

47 Meters Down ends like Fall. Kate dies mid-way through with Lisa only imagining that she has survived. Lisa surfaces alone, her love for her loyal sister intact.

Wait … what? No glance, no motto, no memento, no deception? Just two sisters, trusting in one another to stay alive? How heart-warmingly disappointing.

What A Fan Wants

With 47 Meters Down, I was sure I’d found my next Oops entry. But by the last few minutes, my willing suspension of disbelief was just plain willful. I’d watched the entire movie with my own plot in mind.

Horror fans know a lot. That there will be jump scares, a totally suspected unsuspecting killer, and boobs — lots of boobs. We also expect a lot. We can see through a film that relies on tropes at the expense of a great story. But studying a film isn’t the same as experiencing it. If that film is new to you, you’ll miss out forever on that first-watch feeling.

Discovering a subgenre is still thrilling. In 2019 on my first trip to NYC, I saw a Miskatonic seminar on prosthetic dummy deaths at the great Film Noir Cinema in Brooklyn. I’ll never forget Howard Berger saying: “When you know what to look for in a movie, you can see it coming.” Maybe that’s what planted the idea for Oops and why it just wouldn’t leave.

As a subgenre filled with adventurous final girls, devious friends, and reunions gone terribly wrong, Oops I Effed Your Boyfriend, Now We’re All Gonna Die still delivers. I’d love to find new entries. After all, most horror fans watch movies for something.

To be scared.

To have fun being scared.

To rebel and be weird.

Or to just tune out everything for a while in exchange for that strange, flickering darkness.