NURSE JACKIE. 10 p.m. Mondays, Showtime.

NEW YORK - When it comes to awkwardness, Merritt Wever is a Zen master. As Zoey Barkow, the eager puppy of a junior nurse who trails Edie Falco's character on "Nurse Jackie," the 30-year-old actress can perform a scene over and over with serious focus, all while wearing pink hospital scrubs imprinted with bunnies. During the show's third season, she eats doughnuts without using her hands, stacking them up into a tower and hollowing them out with her teeth.

With her endearing goofiness and flair for slapstick, Wever's defining a new kind of "it" girl - the kind who'd no doubt roll her eyes at anyone who'd ever use the term "it" girl. But over the last few years, she's snagged memorable scenes in indie film favorites such as Lena Dunham's "Tiny Furniture" and Noah Baumbach's "Greenberg," playing the role of the charmingly geeky best friend so believably that Dunham still hangs out with her today. Like Dunham and Wever's "Greenberg" co-star Greta Gerwig, she belongs to a generation of actresses who've transformed a certain slouchy, clumsy, earnest lack of affectation into a legitimate acting technique.

That no-big-deal performance style has elevated her from sidekick to bona fide star on "Nurse Jackie." Watching Wever flop around unself-consciously on screen, it's easy to forget that looking like you're not acting takes a lot of hard work.

When Wever arrives at a cafe in Brooklyn, looking fresh-faced, she seems far more reserved and soft-spoken than Zoey - which might be why it's so funny to see her transformed into a brash creature on screen.

"I like getting to do physical comedy," she said, in between great, fluffy bites of omelet. "I don't feel like there's that many opportunities for young women my age to get to flail around and become" - her voice suddenly takes on the faux-serious tone of a movie voice-over - "the master of her own comic destiny."

Sometimes it seems as if Wever simply willed Zoey into being. Originally, the character was supposed to be a very conventional medical drama type, and a woman of color. "When Merritt walked in, I almost laughed because it was like 'You're at the wrong audition!' " said Linda Wallem, one of the show's creators. "But then she started reading and my palms got sweaty. She was just like Jackie 20 or 30 years ago. She was Jackie's more innocent self."

Now, Wallem said she and co-creator Liz Brixius occasionally leave the ending of a scene ambiguous, just so Wever can improvise. She remembers the day Wever decided her character should spontaneously hug Jackie (who's not a hugger) for an uncomfortably long time. Seeing Falco's pained expression, Wallem prayed that no one would crack up and ruin the take.

"Merritt will say every word you've written in the script, but then she'll add something totally unexpected, like she'll curtsy, or pat Jackie on the back, and everyone will just lose it," explained Brixius. "Part of what makes comedy work is the element of surprise, and when we're laughing on set, it's usually because, oh my God, Merritt, what did you just do?"

Wever admitted that she's never exactly hated getting attention. Born to a single, progressive mother who used a sperm donor, she used to sit in on the activist meetings her mom held at their New York apartment because, "embarrassingly, it was an audience."

Recognizing her love of performing, her mother enrolled her in everything from dance classes to the children's choir of the Metropolitan Opera. She even sent her to a liberal Jewish summer camp where she sang pro-union, pro-labor songs in Yiddish. It wasn't until she attended LaGuardia Arts high school that she began auditioning in earnest, eventually winning parts in off-Broadway plays. (She still occasionally does theater and will be in a New York production of Tony Kushner's "The Illusionist.")

Though she'd go on to win small parts in "Michael Clayton" and "Studio 60 on the Sunset Strip," Zoey became her breakthrough role. The more subtle her comedy - no one else can do the very slight, confused-cocker-spaniel head tilt like Wever - the more she got noticed.

"I remember in Season 1, some magazine called her a scene-stealer," recalled Brixius. "Merritt was horrified that anybody would see her that way."

Now she's finally embracing it - with that awkward, too-long embrace that Wever does so well. This season, Zoey's emerging more often from behind her tuna-and-raisin-bread sandwiches. She's moved into what Wever calls "full-blown b-friend, g-friend" status with the EMT guy, and she may have another suitor on the way.

Meanwhile, Wever's moving past the bunny scrubs into something a little bolder: frog scrubs. "For a long time, I thought that as long as I wasn't wearing pink scrubs, nobody would recognize me," said Wever, breaking into a crooked smile. "Luckily, it hasn't worked out that way."