By KARYN MONGET

Three decades ago, Calvin Klein triggered debate — and a publicity bonanza — when 15-year-old Brooke Shields purred, “You want to know what comes between me and my Calvins? Nothing.”

These days, that landmark television commercial, which CBS and NBC dropped because of its sexual overtones, seems downright quaint.

From Abercrombie & Fitch ads to Lady Gaga music videos, Web sites and reality TV shows such as MTV’s “The Real World,” sexually charged advertising and media images are bombarding consumers — many of them tweens and teens seven to 18 years old. Though more explicit than ever, they rarely raise an eyebrow.

Brand marketers covet tweens and teens. Girls ages eight to 12 alone generated $6.24 billion in apparel sales last year and spent $407.8 million in the intimates category, according to the NPD Group research consultancy. Apparel spending among 13- to 18-year-old girls last year totaled $25 billion, while intimates generated another $1.2 billion.

Intimates plays a big part in fashion apparel, and younger consumers are growing up faster and dressing more provocatively in padded push-up bras, strapless tops, low-cut camisoles, corset looks, boy-cut shorts, thongs and related items that feature sayings such as Eye Candy and Wink Link by A&F.

“There is a definite sexualization of young girls,” said Marc Gobé, president of Emotional Branding LLC. “They are extremely social and connected, more than any generation before, having been born in the technology cauldron.”

There is an inherent challenge for advertisers and marketers who “straddle the boundaries between children, teens and adults,” Gobé said. “Tweens are a lot more mature today because of technology, and they clearly understand the sexual proposition of the ads they see.”

To a degree, fashion brands are going with the flow of a 24/7 media landscape in which the limits of what images are deemed acceptable are constantly being tested and expanded. And while they are playing a role in communicating suggestive, if sometimes playful, sexually infused messages, brands and retailers are generally reluctant to discuss the impact of what they are doing.

In fashion alone, the tidal wave of sexual images includes underwear ads featuring David and Victoria Beckham and Megan Fox for Emporio Armani, as well as Kate Moss, Mark Wahlberg, Hilary Swank and Eva Mendes for Calvin Klein Underwear.

Even designers have gotten into the act. Although tweens and teens aren’t his target customer, Marc Jacobs bared all for the ad campaign this spring for the new men’s fragrance, Bang, which shows him spread-eagle naked on a silver Mylar bed — with only an oversize bottle of the fragrance strategically placed for modesty’s sake. Tom Ford, both at Gucci and for his own new label, has used sexual imagery to create an aura around the brands, including a full-monty model in his 2002 campaign for Yves Saint Laurent’s M7 men’s fragrance.

“The question is how do you differentiate between entertainment and advertising?” said Robert Passikoff, president and chief executive officer of Brand Keys Inc. “It always gets sticky when you talk about morality.…And there’s a question for retailers, branders and marketers of ‘Should we leverage this [provocative content] to children because we want to make sales?”

Does the sexual emphasis sell?

“I think it depends on what’s selling,” said designer Jason Wu. “I think that overtly sexy certainly sells underwear very well, but when it comes to a designer collection, I think right now we’re at a stage that’s more subdued and subtle.…The idea of overtly sexy advertising was always that it was shocking. But I feel like it’s hardly shocking anymore, because that’s all we see all the time.”

Yet sexually themed material is more available than ever. Music videos, such as Lady Gaga’s street-gang fantasy in “Love Game,” flaunt eroticism, and there is nudity and bed scenes in “The Real World” and “Big Brother” on CBS. A report from the Pew Research Center’s Internet & American Life Project last year said 4 percent of teens who own cell phones and are between the ages of 12 to 17 said they have sent sexually suggestive nude or almost-nude images or videos of themselves through text messaging, and 15 percent said they had received such images of a person they know via text message.

“For something to be [genuinely] shocking, no one could run it,” said designer Michael Kors. “I think the only way to get that kind of attention is to basically turn people off.…You do have to be responsible. But at the end of the day, you have to be responsible for what your brand is, whether it’s how provocative you go sexually in an ad, how young the model [is], how thin the model is. Who’s to say what’s right? I don’t think there’s a consensus — it’s just who do you want to appeal to?”

“Kids are very provocative today,” Kors observed. “Twelve-year-old girls wear high heels. The “Jersey Shore” boys are the new Tiger Beat, the pinups. It’s shocking to think, but they are. It’s hard to go backwards with kids today. How are you going to go backwards?”

Diane von Furstenberg, president of the Council of Fashion Designers of America, said, “You can be sexy and not be vulgar. You can do interesting things without becoming a prude. But that’s not just fashion, anyone should be aware of that, whether it is with teenagers or adults.”

A&F, a pioneer of the genre with its late-Nineties catalogues showing teenage girls and boys together in their underwear, continues to push the envelope. Last year, the teen retailer featured an online ad of a young girl in a Gilly Hicks bra and panties with her hands on the buttocks of two nude men who are among a group facing away from the camera. The A&F Web site currently shows a portrait of a young girl nude from the waist up, with an arm across her breasts, on its Intimates link.

“We design and market each of our brands to specific ages, although we are aware that today’s youth identifies and aspires to be older and more sophisticated,” a company spokeswoman said. “The Gilly Hicks girl is 20 years old and has a fun, carefree personality. We feel that it’s only natural for tweens to aspire to be more mature than their actual age, especially when it comes to how they dress.”

American Apparel and its ceo, Dov Charney, revel in the specialty retailer’s sexually charged marketing, which has helped shape its hip, urban consumer appeal. The campaigns feature models in underwear, leotards and tank tops, and appear in indie magazines and e-zines, as well as on billboards and style-centric blogs.

“American Apparel images tend to be evocative and honest, and this can sometimes result in more mature themes,” a company spokeswoman said. “However, our product images are about showcasing the product and the ways it can be worn. Basics, like hoodies and T-shirts, are very popular with our tween customers, and we tend to feature basic styles such as these in a mainly garment-centric, catalogue style of portraiture.”

On its Web site, American Apparel describes the suggestive poses as “provocative, real, unpretentious,” adding that the images have “struck a chord with today’s young trendsetters, and [have] drawn us an intensely loyal following, similar to that of Levi’s in the Sixties and Seventies.”

Victoria’s Secret’s young contemporary lounge and intimates brand, Pink, features young women wearing lingerie and holding stuffed animals. The image evokes youth, but Victoria’s Secret said the label is aimed at 19- to 24-year-olds.

This stew of influences, ubiquitous in their availability, is having a profound impact.

“The culture of a brand has been dictated for a long time, defined by its own persona, then pushed onto the audience,” Emotional Branding’s Gobé said. “Now the brand is less important because of the dialogue that exists between consumers, and what makes a brand cool is what this new culture defines. Today, it’s social media, the conversation. You can’t understand your consumer if you do not have a dialogue. Brands have to start to act like friends.…The biggest opportunity for retailers catering to tweens and teens is to have their people talking, tweeting, engaging in a conversation.”

Tweens, in particular, are being shaped by what they see because of their highly impressionable ages, said Robert Thompson, a professor of pop culture and TV at Syracuse University’s S.I. Newhouse School of Public Communications.

“MTV and videos of entertainers like Britney Spears were a very strong influence on setting style and fashion, and it would be inevitable that people would follow that. You definitely see it on TV, and it’s creepy and shocking to see young girls wearing sexy-looking lingerie.” he said. “There is this element of tarting up at younger and younger ages, and it’s being accepted.”

Jean M. Twenge, author of “Generation Me” and co-author of “The Narcissism Epidemic,” said there is a definite “cultural shift in the direction of narcissism and exhibitionism.”

“One would assume that a girl who wants to dress provocatively has low self-esteem,” Twenge said. “It’s the opposite. Girls now have traits of self-centeredness and wanting to get attention. With eight-year-olds now, it’s brazen self-confidence, and often the culture is putting a big influence on them. They’re seeing it on TV and they’re influenced by a celebrity culture. Reality TV stars are the most narcissistic, and it’s a showcase for narcissistic behavior where you are seeing a very distorted perception of what people are like and they are glorified.”

Victor Fornari, director of child and adolescent psychiatry at North Shore University Hospital & Long Island Jewish Medical Center, said the explicit material is sending the wrong message: It’s OK to look sexy at eight or 10 years old.

Citing A&F and Victoria’s Secret, Fornari said: “I see young girls — younger than tweens — wearing strapless or low-cut tops, and you think, What are they wearing and why? Advertisers really have an opportunity and the responsibility to market appropriate fashion without all of the sex appeal. We rely on the good sense of advertisers to make good decisions.”

The core of the issue for young girls and boys is the need for acceptance by their peers, said Adriann Fonstein, a consumer strategist at AMP Agency, a unit of youth marketing firm Alloy Co.

‘The standards of what is appropriate are not what they used to be.…There is an emotional side to brands like Pink that has a personality of being flirty, outgoing and sexy cute,” she said. “It’s about being in.”

Nancy Ganz, creator of the Fashionfantasygame.com, an interactive game site that was created to empower tween girls in fashion design and business, has more than 1.2 million registered users and has been growing at a rate of more than 12,000 new members weekly since launching in November 2008. Tweens comprise an excess of 30 percent of users, and teens are almost 49 percent. The number of digital ads has doubled over the past year with names such as Neiman Marcus, Kohl’s, Macy’s, Target, Nike, Lands’ End, Dove and Cover Girl.

Ganz said she is now being approached by advertisers for adult products such as breast augmentation and KY Jelly, which she has rejected.

“Sex appeal is important to tweens, but they are not allowed to [design sexy apparel] on this site,” she said. “The truth is, Victoria’s Secret is their store of choice. Even my daughter, Rachel, has been buying bras at Victoria’s Secret since she was 13.”