‘Okay, now let’s do ‘Cake by the Ocean!’?”

There were two girls in the locker room changing the other day as I was preparing to take my kids swimming and they had turned the place into a kind of miniature photography studio. Walking around, looking for the perfect light, they held up their cellphones, pushed up their cleavage and made pouty faces while blurting out the themes from pop songs.

In the video of “Cake by the Ocean,” one of the summer’s pop hits, scantily clad women participate in a cake fight while eating and smearing cake all over themselves. Fortunately, the girls in the locker room decided to skip that. They just seemed to be opening their mouths as wide as possible for each picture.

The scene was both absurd and sad. But no matter how much I gave them the stink eye, they weren’t the least bit embarrassed.

In retrospect, I realize that I should’ve taken the approach of Chris “Burr” Martin, a comedian from Spokane, Wash.

Martin wasn’t happy with the pictures his 19-year-old daughter was posting. So he asked her to “Just tone it down a little bit,” Martin told KXLY. “Well she didn’t. So I thought, ‘Well, I’ll show you what it looks like, then.’”

The results, in which Martin imitated his daughter’s sexy poses, went viral. The less-than-svelte, middle-aged guy with a little stubble recreates his daughter’s outfits — from tank tops to tattoos — and then imitates her “duck face” as she poses with pouty lips for the camera.

In one, he draws her belly art on his belly and then takes a selfie in the mirror — just like she does — showing not just her revealing poses but also the deep narcissism it takes to be constantly engaged in this behavior.

It’s not that teenage girls didn’t spend plenty of time primping in the mirror before the invention of the iPhone. Of course they did. But now they’re taking hundreds of pictures of themselves each week and curating them to determine which one puts them in the best light (literally and figuratively).

A girl used to primp before going to school or the pool or a dance. But once there, the hope was that they could focus on what was happening in class or enjoy themselves. But now they need to take a half-hour out of a fun afternoon to create a professional photo shoot.

In the past week, I’ve watched girls take selfies in the CVS makeup aisle, at Stop & Shop (in the bakery department — Cake by the produce section?) and on the train next to me.

And it’s about to get worse. Apparently SnapChat recently acquired the company Seene, an app which will allow us to send 3-D selfies.

It’s nice that because we’re in public I don’t need to witness the “noodz” kids are so fond of sending these days. At least these pouty-faced selfies aren’t going to be sent around school and used to blackmail girls into doing God knows what.

But the impulse behind them is the same — and so are the effects. The selfie culture has made girls even more anxious about their appearances than they were before.

“The mental-health outcomes that we’re starting to look at now are things like body dysmorphic disorder, obsessive-compulsive disorder, depression and anxiety,” David Proost, a child psychologist told US News. “We are starting to see those things creep up and be related conditions to excessive [social media] use.”

Those like MIT’s Sherry Turkle, who decades ago heralded the virtual world as allowing kids and adults to experiment with their personas, have become chastened.

When Howard Gardner and Katie Davis interviewed camp directors as part of their research for “The App Generation,” they found that “campers today demonstrate more self-confidence in what they say they can do but are less willing to test their abilities through action.”

Those interviewed “attributed this shift to youth’s growing distaste for taking any tangible risk that could end in failure — failure that once might have been witnessed by a few peers and then forgotten but today might become a part of one’s permanent digital footprint.”

As of Friday, Martin had 16,000 followers on Instagram and his following was growing by the hour.

If we can’t get our kids to realize the harmful effect of selfie culture by reasoning with them, maybe it’s time to pull out that old parenting standby — humiliation.

Naomi Schaefer Riley is a senior fellow at the Independent Women’s Forum.