It’s not a new movie trope, but seriously — how do you make “Hot for teacher” an acceptable subject for a movie nowadays?

“My Teacher, My Obsession” whistles past the #Notlegal graveyard with horror.  Well, with a stalker/thriller, anyway.

That’s what the prologue promises, a school janitor walking in on what looks like a sexual assault, a bloodied eyewitness yelling “RUN.”

But then comes the flashback, the hour long drift into exploitation, titillation and prurient bumping and grinding. Having it both ways, we call that.

Riley (Laura Bilgeri) is braced for another school year and another high school for English teacher dad Chris (Rusty Joiner).

But the girls at Frost High might have other ideas. Tricia (Alexandria DeBerry), blonde Queen Bee and her popular pretty girl classmates purr that they’ll have him “wrapped around” their fingers.

Kyla (Lucy Loken) is the one to watch out for. She’s kind of quiet, an 18 year-old yearbook photographer who has polished the bedroom eyes and vocal fry of the teen temptress.

After a couple of scenes where Chris establishes his “hip young teacher” bonafides (checking his students’ cellphone playlists) — “I remember what it’s like to be young and pretend not to care.” — Kyla’s plot is set in motion.

Befriend Riley, poor-mouth the other girls who might get in the way, sabotage her mother’s hopes for a “normal” relationship with the single teacher, plant photos, etc.

It’s laugh out loud ludicrous, almost from start to end.

“I’m 18. I’m free to do what and who I want.”

The adults are gullible and somewhat hapless when faced with this potentially lethal Lolita.

Teacher Chris? He walks — or drives — right into this. This is what happens, educators, when you don’t remember Sting singing “Don’t stand so close to me.”

Loken, of TV’s “Teen Wolf,” does her damnedest to measure up to the gold standard of dangerously obsessed high school girls — Erika Christenson’s oversexed/lethally libidinous “Swimfan.”

A very wooden (no pun intended) Joiner has to play a grown man helpless trapped in her web of aggressive come-ons and one-liners.

“Consider that my thesis statement!”

“Pick up that jar, sugar. I’m legal!”

The most generous way to look at this sort of film USED to be middle-aged male wish fulfillment fantasy. And that is generously creepy. It’s always doubly unsavory when a man scripts it.

But even without the “ick” factor, “My Obsession” gives away the game too easily, makes the seemingly-nerdy girl who still shoots on film too obviously a predator, wastes too much time in the middle acts with us knowing what is coming.

And if you’re going for “over the top,” Ms. Loken, there’s no value in going halfway.

MPAA Rating: TV-14

Cast:Lucy Loken, Laura Bilgeri, Rusty Joiner, Alexandria DeBerry

Credits:Directed by Damián Romay, script by Patrick Robert Young . A MarVista.Netflix release.

Running time: 1:26