Calvin Klein Reflects on His '80s Muse Brooke Shields: 'Our Ads, and of Course Brooke, Became Iconic'

Calvin Klein is reminiscing about his iconic ads featuring '80s "It Girl" Brooke Shields. The actress-supermodel was 15 years old when the campaign first launched and fresh off two hit films, The Blue Lagoon and Pretty Baby.

"Brooke has a fresh, sexy beauty," the designer, 80, tells PEOPLE.

"When we first met, she was a teenager, two years after filming Pretty Baby," he remembers. "We were launching jeans and wanted to say something new."

"Brooke was the perfect fit — young and confident with a modern spirit," recalls Klein.

"Our ads, and of course Brooke, became iconic," Klein says. "Who doesn't remember? You want to know what comes between me and my Calvins? Nothing," he says, reciting the campaign's memorable — and controversial — tagline.

"It was fun, innocent and yes, sexy as hell," he adds.

At the time, the tagline had a different meaning to Shields. As she recalls, "Even the line, 'You want to know what comes between me and my Calvins? Nothing.' I had a dog, and I would say, 'Nothing comes between me and my puppy.' It was an expression."

"I didn't think of it as, I'm not wearing any underwear," says the 57-year-old actress and beauty icon.

"It just felt like we were a part of an inspired campaign," she continues of the ads, which were shot by famed fashion photographer Richard Avedon.

"There was so much homework in doing those commercials, and there was so much to memorize and perform," she says. "And they didn't have teleprompters or anything like that. It was so much fun to perform and memorize."

The ads created a media sensation, made Calvins the hottest jeans on the market and were so controversial they were even banned in several countries.

The mom of two remembers coming back from Europe and hearing of the ban. "I was like, 'They're smart. Why do the smart things get banned?'"

Shields also remembers Klein being sweet on set. "He could not have been nicer to me. Kinder, sweeter, caring."

Looking back, she admits she understands the controversy. "I can understand it now, where it's coming from. But for some reason, and maybe it's just protection, I'm not mad at it. It afforded me a lot."

After all, she says, "Sex sells. Sex has been selling since the dawn of time and it still does."

Brooke Shields: Pretty Baby premieres April 3 on Hulu.