When Jane Fonda approached Dolly Parton to co-star in 9 to 5, the legendary country singer had one demand. "I said, 'well, this is a good opportunity, but I'll only do it if I can write the theme song," Parton, who'd never acted in a film before, explained. From there, the Tennessee native took matters into her own hands — literally. During downtime between takes of the 1980 comedy about women in the workplace, starring Parton, Fonda and Lily Tomlin, Parton would walk around the set "playing" her acrylic nails like a washboard.

“I always play the nails and I’d come up with little things that I would see on the set, like I tumble out of bed and I stumble to the kitchen, pour myself a cup of… And I thought, 'Wow, that sounds like a typewriter,'" the nine-time Grammy winner explained. The clacking baseline heard at the beginning of the track was all Parton. The record's credits even read "Nails by Dolly," according to the musician.

Lily Tomlin Dolly Parton Jane Fonda

Lily Tomlin, Jane Fonda and Dolly Parton on the set of "9 to 5"

Parton's role was 'modeled on her personality'

When Fonda initially came up with the idea for 9 to 5, she had Parton in mind from the very beginning. The Oscar-winning actress recalled driving home from her first meeting with Tomlin when Parton's 1978 hit "Two Doors Down" came on her car radio. "It was pow, it was a visceral sense that Dolly Parton had to be a secretary in 9 to 5," she revealed. "I suddenly [got] an image of Dolly Parton sitting at a typewriter. And I thought that would be something, to have Dolly Parton in her first movie playing a secretary in a movie that, among many other things, is going to touch upon sexual harassment. She's perfect."

Fonda added that Parton's character, Doralee Rhodes, was "kind of modeled on her personality." She further noted that the musician "grew up poor in the sense of material advantages so she knows what it feels like to be put upon, to be challenged, and I'm sure she’s been sexually harassed in her life."

Despite never having taken an acting lesson in her life, Parton wasn't afraid to appear alongside such seasoned actresses. Calling 9 to 5 "a joy to make," she explained she "wasn't intimidated by them" because she has several sisters and it was "just like having two new girlfriends."

According to Tomlin, the trio had an "instant camaraderie" and, upon the start of filming, had several pajama parties at the Beverly Hills Hotel. Even then, she claims she never saw Parton without a wig. Fonda echoed those sentiments, adding that the musician even came out of her bedroom all made up with all her "regalia." Parton didn't shy away from letting her hair down, metaphorically speaking, however. "You cannot finish a day with Dolly without laughing so hard that you have to cross your legs," Fonda joked.

Parton's costars got 'goosebumps' when they first heard "9 to 5"

Parton first sang an early version of "9 to 5" for Fonda and Tomlin when they were just outside the movie set. "Lily and I looked at each other and we had goosebumps," she remembered. "And we knew, this is not just a movie song, this is an anthem."

Added Tomlin: "Jane Fonda and I were just flabbergasted; we thought it was so great. I said to Jane, 'This will make the movie a hit, if nothing else.'"

After that, Parton says she purposely spread out the rest of the songwriting process, as the women excitedly asking on a daily basis what else she'd written became one of the trio's "little fun things" or hobbies. In the end, Parton claims to have penned 100 verses made up of "real things that happened," including comedy and other lyrics she knew would never make the final cut. When it came time to finally record the song, Parton even invited her castmates to perform background vocals.

Dolly Parton 9 to 5

Dolly Parton in "9 to 5"

The theme song went on to win two Grammys and snagged an Oscar nomination

The rest is history. Parton released “9 to 5” as a single in November 1980, and included it both on the film's soundtrack, as well as on her album 9 to 5 and Odd Jobs. Not only did the RIAA Platinum-certified track top the Billboard Hot 100 chart in February 1981, but Parton also went on to win two Grammys and earned a best original song Academy Award nomination.

The film itself was similarly successful. Released in theaters on December 19, 1980, 9 to 5 earned more than $100 million at the box office and became the second highest-grossing movie that year, trailing only Star Wars: Episode V - The Empire Strikes Back. In the event that her film debut had flopped, however, Parton joked she would've pointed the finger at Fonda and Tomlin since they were already "huge" stars: "I always thought, 'well, if it's a big hit, then I would get the glory of it like them, with Lily and Jane, and if it’s a flop, I can blame it on them."

Following her debut in 9 to 5, Parton went on to add dozens of acting credits to her expansive resume, including roles in such films as The Best Little Whorehouse in Texas and Steel Magnolias, while also still selling millions of records. As Tomlin summed up: "Being in 9 to 5 just showed Dolly’s versatility. She was a big musical star, and now a movie audience with a huge hit as 9 to 5 was, just makes her better, a queen, an empress."