Marianne Rendon, 17, a senior at The Ursuline School in New Rochelle, is likely unaccustomed to being treated the way her character is treated when she makes her entrance in “Once Upon a Mattress.”

When Princess Winnifred the Wobegone enters, fresh from the swamp – and anything but fresh – she’s also just swam the moat.

“Everyone is like, ‘Get away from me. You’re smelly. You just came out of the swamp,’” Rendon says.

Is Princess Fred discouraged?

Not one bit.

She sets about singing “Hey nonny, nonny, is it you?” wondering where her husband-to-be might be.

“That’s the great thing about her. She doesn’t care,” Rendon says. “She’s not afraid to be who she is.”

It’s a message that’s particularly well-suited to the audience at Ursuline, an all-girls school, Rendon says, “especially with this age group, because it’s about being an individual and who you are and not being afraid to say that I’m silly and who I am.”

There’s a lot of physical comedy – “I fall off the stage into the pit,” she says – and Winnifred runs all over the stage.

The role made Carol Burnett an overnight Broadway sensation in 1959, but it’s unlikely that a 17-year-old in 2008 would know Carol Burnett, right? Wrong.

“I’m a huge Carol Burnett fan,” she says.

This retelling of “The Princess and the Pea” fairy tale is set to the music of Mary Rodgers, the daughter of Broadway’s Richard Rodgers.

There are the 20 downy mattresses that Winnifred gets to sleep on – or not sleep on – as she seeks to prove to the evil Queen Aggravain (Tess Gardephe) that she’s a bona-fide princess.

The queen cheats a bit, Gardephe says, trying to make Princess Fred so tired that she couldn’t possibly feel the pea beneath the mattresses. She throws a ball in her honor, and there are sleeping potions, incense and lullabies.

“I’m really, really sure she won’t pass the test,” Gardephe says.

If she does pass, she’ll marry Aggravain’s son, Prince Dauntless the Drab, played by New Rochelle High School junior Zach Gray.

Gray is making a guest appearance at the all-girl-school’s musical, having worked with director Edie Ann Reidy at Albert Leonard Middle School on “Barnum,” “The Wizard of Oz” and “Seussical.”

He says the lines were challenging but that a New Rochelle classmate, Natalie Fontecchia, helped him master the memorization.

“I owe her a lot,” he says.

As Dauntless, Gray wears a royal blue doublet and tights.

“I’m a wrestler, so I’m used to the tights. It’s the pants I’m not used to,” he says.

Another guest performer is Noah Rauschkolb, a Mamaroneck High School sophomore who takes part in his school’s intensive acting program, Performing Arts Curriculum Exchange. Reidy was also a PACE kid when she attended Mamaroneck and she asked theatrical guru John Fredericksen to “send a kid over,” Rauschkolb says.

Rauschkolb was the kid and he plays Sir Harry, whom he describes as “Mr. Perfect,” Dauntless’ friend.

A decree states that until Dauntless marries, no one in the kingdom may marry. Since Harry wants to marry Lady Larkin, he sets off to find Dauntless a bride. He finds Winnifred in the swamp.

Other would-be brides and grooms help, sticking other bumpy things between the mattresses to keep the princess awake.

Rendon says the challenge to Winnifred is in playing a character who comes off as so simple.

“She seems a little vacant at first and you have to think of ways she’d want to (speak),” Rendon says.

“In the fall, I played the Katharine Hepburn part in ‘The Desk Set,’ and you can pretend that you’re that smart but it’s harder to be like ‘Yeah, I’m not thinking at this point,’ ” she says.

“Still, she’s completely genuine and sincere,” Rendon adds.

And completely happy to be who she is.

Hey nonny, nonny, what a role.

Photo by Tania Savayan/The Journal News: Senior Marianne Rendon, 17, as Princess Winnifred sings “Shy” during rehearsal for “Once Upon a Mattress” at The Ursuline School.

“Once Upon a Mattress”
Where: The Ursuline School, 1354 North Ave., New Rochelle.
When: 7 p.m. today, tomorrow and Saturday.
Tickets: $10.
Call: 914-636-3950.
With: Marianne Rendon, Tess Gardephe, Chelsea Russo, Michelle Fufido, Noah Rauschkolb, Jillian Sayegh, Zach Grey, Caitlin Rossi, Ryan Lauroano, Brian Bainbridge, James Florakis, Jorge Flores, Rebecca Bitondo, Rquel Reciti, Caroline Farina, Madeline Barry, Dana Barry, Veronica Checksfield, Rachel Curland, Christina Greco, Andrea Marano, Kristina DiOrio, Charlotte Haughney, Cailean Geary, Teresa O’Grady, Kaitlin Lauroano, Kerry Fenn, Becca Curland, Gaby Marano, Natasha Herrick, Stephanie Crischone, Caroline Minassian, Catherine Castro, Emily Houghton, Sophia Sayegh, Amanda Malean, Madeline Gallagher, Maria LaGumina.