As the Grammy Award winner began work on the exuberant "Kinky Boots," it took her back to her childhood, where she was likely to be found listening endlessly to cast albums on a record player.
There was "There's No Business Like Show Business" and "My Fair Lady." And "South Pacific," of course. She remembers her grandmother coming downstairs and ripping "The King and I" off the player after one too many spins.
"My mother said I was a little odd as a kid," says Lauper, 59. "I was alone a lot but I didn't feel alone. When I sang with those records, I'd be Julie Andrews and there was Rex Harrison sitting on my mother's bed. I was Mitzi Gaynor. I was Ezio Pinza. I think she had Mary Martin, too—I was all of them. I was pretty good until they sang duets."
Sitting backstage at the Al Hirschfeld Theatre, waiting to catch another preview of her 15-song debut as a Broadway lyricist and composer, Lauper is both nervous and humble. The little girl who listened compulsively to show tunes has now delivered her own.
"It's the closest thing to being 5," she says.
"Kinky Boots," which opens April 4, is based on an obscure 2005 British film about a British shoe factory on the brink of ruin that retrofits itself into a maker of fetishistic footwear for drag queens.
The musical version has a reworked story by Harvey Fierstein.
"I keep telling myself how lucky am I that the first thing I do on Broadway has Harvey and Jerry and Stephen Oremus—everyone a Tony winner," Lauper says. "C'mon, that's awesome!"
This isn't the first time the "Girls Just Want to Have Fun" singer has been asked to compose music for the stage. It took her old friend Fierstein, the book writer for "La Cage aux Folles" and "Newsies," to lure her out.
His new story helped: Fierstein has teased out the friendship between the straight factory owner and the factory-saving transvestite who suggests the boot switch, who bond over their harsh fathers.
The show embraces acceptance and tolerance, things long championed by Lauper, whose True Colors Fund has called for an end to gay, lesbian, bisexual and transgender youth homelessness.
"It's about outsiders, it's about people overcoming their differences for the greater good. Of course this would speak to me," she says, laughing. "Who the hell else would it speak to?"
Lauper and Fierstein have developed a joking mentor-mentee relationship that draws on the classic "Mommie Dearest" film. Fierstein calls her "Tina" and signs his notes "Mommy."
Fierstein says converting a pop composer into a Broadway one wasn't easy but Lauper was game. He needed songs that propel the action rather than restate a theme, as pop tunes do. He also needed to teach her that a song can be good but it might not fit the space needed.
"The more talented the person, the easier it is to work with them," he says. "She's used to having to fight. So the hardest thing for her I think was to say, 'Oh, they're not fighting me. They're helping me.'"
The daughter of immigrants from Palermo, Italy, Lauper was born in the New York borough of Queens and raised in Brooklyn, acquiring her signature thick accent. She began performing in 1974 with a local Long Island band, then formed Blue Angel in 1978.
After the group's debut album bombed in 1980, the band split up. Lauper went to work in a clothing store and sang Top 40 tunes at a Manhattan bar. Then came the wild success of her 1983 debut LP, "She's So Unusual," from which the single "Girls Just Want to Have Fun" was taken.
Her music since then has gone in many directions. On "Sisters of Avalon," Lauper collaborated with Jan Pulsford, former keyboard player in the Thompson Twins. On "At Last," she tackled pop standards. And she explored the blues in her recent "Memphis Blues" CD.
That experimentation helped when she was asked to write different styles for different characters in "Kinky Boots." But Lauper insists she just followed orders.
"I like to make people laugh. I like to make people think and cry. I like the characters to have depth and Harvey writes them with depth," she says. "I don't know what I'm doing. I just follow what they wanted."
Someone wanted a song with the refrain "Yeah!" so she wrote "Everybody Say Yeah." Fierstein wanted a duet by the two male leads about shaking free from their dads, so she wrote "Not My Father's Son." Watching the film "Kung Fu Panda" with her 15-year-old son triggered the song "The History of Wrong Guys."
She says songs just come to her, whether she's at the gym or in bed. When they do, she reaches for her iPhone and sings into a recorder. "Sometimes they come in an idea, sometimes they come in a song, sometimes you wake up in the middle of the night."
Music hasn't always been able to contain Lauper, who won an Emmy in 1995 for a guest role on the NBC show "Mad About You." She starred on Broadway in "Three Penny Opera" alongside Alan Cumming in 2006, wrote an autobiography, and last year starred in her own reality show, "Cyndi Lauper: She's Still So Unusual" on WE.
Now she's challenged herself with a Broadway score. "I found it fantastic and I think I'm a better songwriter for it, too," she says before putting a knit cap on and disappearing into the theater to watch the show.
"I gotta go hide," she says.
Follow Mark Kennedy on Twitter at http://twitter.com/KennedyTwits