Bob Mackie Says Cher's Style First Shifted When She Became a 'Married Teenage Girl': 'She Was Ready' (Exclusive)

The subject of the new documentary 'Bob Mackie: Naked Illusion' looks back at the evolutions of Cher's style over their decades-long friendship

Bob Mackie says Cher always had a strong sense of style — even before she started thinking about it.

Speaking with PEOPLE about the new documentary, Bob Mackie: Naked Illusion, which looks back at his life and career, the iconic designer, 85, tells PEOPLE that Cher has been a "simple girl" since the day he met her in 1967 on The Carol Burnett Show. (Mackie was Burnett's costume designer.)

"She has this thing about affecting people where they're wanting to know more about her and whatever," he says. "She was a simple girl — just beautiful, but a simple girl."

From the start, it was clear to Mackie that Cher had something "special" and a strong sense of style.

"When I first met her, she knew her look. She had her bell-bottoms and her fur vests and her little funny, quirky things, but she'd made that all up herself," Mackie recalls.

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Related: Cher Recalls 'Loin Cloth' Oscar Outfit (and Jane Fonda's Reaction) After Being Snubbed: 'My F--- You Moment'

"She'd dress Sonny [Bono, her first husband] up, and they'd go out and do their songs. She never thought about any other kind of clothes really. She wore what trendy things teenage girls wore, but then all of a sudden, she was a married teenage girl."

Cher married Bono in 1964 at age 18; they divorced in 1975.

When it came to that first style transformation, Mackie says Cher was "just ready to do it."

"She was ready to get dressed up," he adds. "She loves to get dressed up. It's just interesting how some people don't really care about it one way or another, but she... Give her something fun to wear, and she's happy. And you see that."

In the documentary, the two look back at Cher's 1986 Academy Awards outfit, explaining the outrageous look was a response to critics who didn't believe she carried herself like a "serious" actor, despite having been nominated two years earlier for her acclaimed performance in Silkwood.

"She said, ‘I’m giving out this award, and they haven’t seen me look like I used to look.’ Because she had been making movies and these movies where she was playing kind of down and dirty characters. Silkwood and you know, she wasn’t glamorous, so they hadn’t seen her get all dressed up," Mackie recalls in the doc.

He notes that for Cher, "to get dressed up didn’t mean her putting on a pretty dress. It meant, you know, a good outfit. And I had my sketch pad, so I started drawing. And I drew a little bit because I knew I probably wouldn’t see her for a month or so, so I had to get it all moving."

Cher recalls being interested in "big feathers," adding, "I said, ‘I just want—,’ and he said, ‘Don’t say anything else.’ We had a short time with each other, too.”

Mackie continues, laughing: “I said, ‘Should it have a loin cloth?’ And she said, ‘Ooh yeah, I want a loin cloth.’ ”

Cher would go on to win the best actress Oscar two years later for Moonstruck.

Bob Mackie: Naked Illusion is now streaming on Prime Video.