Slut pages. Sink shots. Yik Yak. Finstas. Kik. Snapchat. Revenge porn. Tinder food stamps.

If that reads like a different language, chances are you’re not an American teenager on social media.

It’s this world — a chaotic mix of nude photos, cyber-bullying and dysfunctional relationships — that author Nancy Jo Sales ventured into when researching her new book, “American Girls: Social Media and the Secret Lives of Teenagers” (Knopf).

Sales has been studying the lives of American teenagers since the 1990s. During her 2½ years of research for “American Girls,” she was alarmed, though not shocked, by what she found. (Most adult readers will be shocked, as Sales points out, by how wildly the adult experience of social media differs from that of a teen. An adult might be on Facebook and Twitter, but they probably haven’t even heard of most of the apps that teens use, let alone how they use them.)

“What’s being expressed on social media has been percolating in our culture for decades,” Sales tells The Post.

“But I was really troubled by the sexual harassment of teenage girls. It’s something that happens online on a daily basis — sometimes an hourly basis. And it’s so common, it’s become a regular part of teen culture. You’ll read an article about ‘sexting rings’ but what these articles miss is that it’s not at just one school. It’s happening at every school I researched. It’s become so common.”

Other aspects of teen culture Sales discusses in the book: slut pages, where nude photos of a girl, originally sent to one boy, are distributed to others — i.e., a sexting ring — and then posted on Instagram accounts like “[Name of School] Hotties” or “[Name of Town] Hos” for everyone to view and comment on, often dismissively. This is typically followed by a kind of schoolwide shaming (of the girl — never the boy) that calls to mind the tarring and feathering of Puritan New England, as was with a case from Boca Raton, Fla., which Sales details in the book.

Recounts 13-year-old Julie: “[My sister’s friend] was having a hard time, she was acting out. She’s a senior in high school and she was caught giving head to a boy — it was at a party and somebody walked in and took a picture and it went all over social media. And so many people were hating on her in the school and she literally had no friends left except my sister. She was being called a slut and it got to her really badly, cause she suffers from anxiety and depression, and she wanted to kill herself.”

A finsta: A fake Instagram account created under a different name, so that parents won’t know what their teens are up to online. “Especially if it’s like sixth-grade girls posting pictures in their bras. Or like they use them to talk crap about each other,” clarifies 15-year-old Kayla from Boca Raton in the book.

Tinder food stamps: Using the dating app to exchange sex for free meals and other items, a sort of soft prostitution that has become normalized by social media. “Some sugar babies have Amazon Wish Lists where they tell their sugar daddies what they would like to have,” Sales writes. “Everything from jewelry to silverware to furniture to magazine subscriptions.”

The sink shot: When a girl takes a selfie in a bathroom mirror, often in a thong, and poses with her behind propped against the sink, so that it will appear larger. Not surprisingly, Kim Kardashian popularized this sort of shot, also known as a “belfie,” or butt selfie.

Revenge porn: When a couple breaks up and the boy passes around nude photos the girl sent him in confidence.

Yik Yak and Kik: just two of the seemingly countless anonymous messaging apps that allow users to communicate with each other. Kik was the app cited in the January murder of 13-year-old Nicole Madison Lovell in Blacksburg, Va. The day before she died, Nicole showed neighbors Kik messages she had exchanged with an 18-year-old boy she was to meet that night. Two Virginia Tech freshmen are currently accused of her premeditated kidnapping and killing.

What Sales makes clear is just how prevalent social media is in the life of an American teenager. It’s not an occasional hobby, and most of the teens Sales spoke to told of how they were “addicted,” “obsessed” and “couldn’t stop” looking at their phones.

“For most American girls, social media is where they live,” writes Sales, who spoke to over 200 girls ages 13-19 from Manhattan to Florida, Arizona, Texas and Kentucky.

“We’re on it 24/7,” a 13-year-old girl in Montclair, NJ, told the author. “It’s all we do.”

And while teenagers have certainly always had sex, experimented with drugs, bullied each other and gotten into trouble, Sales is concerned by the way that social media magnifies these existing tendencies and makes young women matter less — they have less agency, less inclination to speak up about the online behavior that has become so prevalent.

“We’ve evolved to communicate face to face. Our communication occurs more with nonverbal cues, body language,” says Sales. “There are studies showing that kids now are less able to have a conversation and make eye contact. So how does this affect girls? Well, whenever you have a situation in which people are dehumanized, women and girls suffer more. We are already more objectified. It becomes easier [for boys] to see someone as a thing, rather than a person.”

Case in point: the widespread demands for nude photos, sometimes by a crush or boyfriend, but often just from a random guy at school. (“Snapchat me that p—y if it’s cool” goes the refrain in the Yo Gotti song “Down in the DM [Direct Message]” wherein a man messages another man’s girlfriend requesting nudes after seeing a photo of her BMW on Instagram.)

“They have conversations with boys who [ask for nudes] and they think, ‘Maybe this is how I have a relationship,’ ” Sales says. “And one of the girls told me that if you respond by saying, ‘How dare you?’ or get angry, they say you have no chill.”

As 13-year-old Sophia explains to Sales in the book: “‘They judge you if you don’t send nudes like you’re a prude. But if you just laugh, then they’ll be aggravated, but they won’t do anything bad to you . . . [such as] start rumors. Pretend like you sent them a naked picture they got off the Internet and it’s not even you.’ ”)

In a chapter called “Thirteen” (all of the book’s chapters are named for the age of the girls discussed therein), Sales describes Riley, Sophia and Victoria coming out of middle school at the end of the school day in Montclair. The girls are all crowded around Riley’s phone, which displays a screenshot of a Snapchat from a boy at school named Zach, asking her for nude photos.

This, it turns out, had been happening almost daily after Riley’s ex-boyfriend, Danny, had spread a rumor that she had given him oral sex. The rumor was untrue, started by another girl who had told Danny that Riley was flirting online with other guys. The girl had clearly hoped to cause a breakup, and did — after which Danny took to social media. “He called me a slut,” Riley said, “and everyone thought I was a slut and everyone started to hate me about that on social media. Like on Ask.fm.”

Ask.fm is a popular question-and-answer website and app where teens go, as a 2013 CNET article by Jennifer Van Grove put it, “to escape the built-in accountability of Facebook.” It allows anyone to post comments and questions to a user’s profile. “Want to know more about your best friend or your crush? Looking for good advice on how to handle life’s little challenges? Just want to ask an inspiring person you’ve never met on the other side of the world about their lives? Go for it! Others will ask you in return, about anything,” claims the official Ask.fm FAQ section.

Unfortunately, it’s also become the perfect forum for cyber-bullying and harassment. The app has been linked with at least seven teen suicides, according to an anti-bullying organization called No Bullying, including a 14-year-old named Hannah Smith from Leicestershire, England, who was routinely taunted by anonymous commenters who said things like “every[one] will be happy if u died,” “drink bleach” and “go die.”

Hannah hanged herself in August 2013 after receiving vile messages from Internet trolls for months. However, it has been reported that Hannah possibly sent many of these messages to herself and that she engaged in self-cyber-bullying, a phenomenon best described as the virtual equivalent of cutting. Her parents have since become vocal advocates for the regulation of anonymity online.

Sales, who lives in the East Village, has a 15-year-old daughter who helped focus her research for the book. “She clued me in to a lot of stuff that was happening,” Sales says. The experience of researching and writing the book impressed upon her the necessity of having a conversation with her daughter — not just one, but an ongoing conversation about what was happening on social media.

“I never lost my sense of what it is to be a teenager, I’m not sure why,” Sales says. “Some of these things are painful. One thing that’s important to do as a parent is remember what it felt like and tap into that. They’re just coming of age, they’re experiencing these things for the first time. There needs to be a great deal of compassion when you try to put yourselves in their shoes. I try and think, ‘She’s telling me this story, and how would I feel if this were happening to me?’ So instead of coming at it from a point of judgment or alarm [as a parent], I try to get rid of the fear of what you’re hearing and just listen.
“People keep saying, ‘What am I supposed to do, take away her phone?’ No, that’s not what I’m saying in the book. Talk to [teens] about what they do on their phones and how much they’re on them.

“It’s a challenging landscape, much of it unprecedented in our experience. And I feel we all have a responsibility to guide our daughters and sons through it.”

While young women might have a tougher time on social media, it’s up to parents of both genders to take an active role in talking to their teens about what’s going on.

While some teens have stepped out of the social media loop altogether — 19-year-old Instagram star Essena O’Neill made headlines in the fall by quitting the app, saying, “social media is not real” — most don’t.

“I spoke to girls who said, ‘social media is destroying our lives,’ ” Sales says. “ ‘But we can’t go off it, because then we’d have no life.’ There’s this whole perception that [teenage girls] love social media, but in many ways they hate it. But they don’t stop, because that’s where teen culture is happening.”