Photo: Andreas Laszlo Konrath. Makeup by Garret Gervais at Opus Beauty, using Dior Addict. Hair by David Gardner/Solo Artists.

Where most people see the dressing room of a Soho clothing store, ­Alison Brie sees a stage with an open mike. “Oh, man, this would be my costume if I were playing a janitor in a mental institution,” says the actress, whipping open the curtain to reveal a dark sack of a dress with an unflattering bulge below the waist. “But there’s something about it I kind of dig. I’m considering it. For around the house only. And for when I’m doing a cleaning service on the side of a freeway.”

She returns to the fitting room and tries on the same dress, this time in a brick-colored pattern with little dogs on it. It’s just as ill-fitting, but Brie seems disappointed it doesn’t look worse: “Instead of being like, ‘Nope, this one’s a no,’ I’m like, ‘Check out why this sucks!’ Look. What is this? I can’t deal,” she says, turning to one side to accentuate the erect material near her crotch. “It’s like a fabric penis!”

Unlike the uptight characters she plays on two of TV’s most critically beloved shows—she’s Pete Campbell’s traditionalist wife, Trudy, on Mad Men, and prudish former Adderall addict Annie Edison on Community—Brie is bawdy, fun, and a little shameless. When I casually mention see-through tops, Brie rips open her jacket: She’s wearing one, with a neon-pink bra underneath. “Oh my gosh,” she says. “I’m all about seeing your bra through your clothes.”

She’s slightly truer to form in this month’s romantic comedy The Five-Year Engagement, in which she plays Emily Blunt’s wacky, scene-stealing younger sister who gets knocked up and shotgun-married. But Brie insists, “Certain precautions can be taken to make sure that doesn’t happen. I am not as irresponsible as that character.” Also, while at the Sundance Film Festival for Save the Date, the other wedding comedy in which she ­appears this year, someone asked her and co-star Lizzy Caplan who would get married first. “Both of us were like, ‘Not it! Not it!,’ ” Brie says. “We’re on the same page about that.”

If you want to see Brie play herself, check YouTube: A video of her singing Hall & Oates’s “Rich Girl” with her newly formed band, the Girls (Who Sing Other People’s Songs), recently went viral, as did a clip of her expertly preparing an egg-salad sandwich with her feet while guest-hosting G4’s Attack of the Show (and then gamely nibbling leftovers off her co-host’s toes).

“I’m actually pretty good at doing stuff with my feet,” says Brie. “I shouldn’t say that in an interview, because foot-fetish people are going to get crazy.” She’s not kidding. “On Twitter they post pictures of my feet and ask what color my toenails are painted. It’s very flattering. I support foot fetishists. If that’s what you’re into, great. Great that you know that about yourself and you embrace it.”

Brie says both of her TV characters and the exasperated bride she plays in Save the Date are based in part on her older, perfectionist, financial-adviser ­sister, Lauren—“She’s like Martha Stewart; she hosts Thanksgiving at her house, and her place settings are amazing”—but more of her own up-for-anything personality has gradually seeped through. Mad Men’s newly suburban Trudy “really goes for the frumpiness,” she says. “I don’t think she sees it as a bad thing or like, ‘Wow, I really let myself go. I’d better bounce back.’ She’s discovering this other side to herself that she enjoys. Pete’s just not into it. Go figure.”

And Community’s Annie is finally giving up “operating with this whole mannequin guise of having it together when everything underneath is simmering and about to explode.” Now that she’s moved in with Abed (Danny Pudi) and Troy (Donald Glover), says Brie, “I feel like any progress Annie has made toward adulthood has been thwarted and she’s just regressing more and more each week. In a good way.”

Rather unsurprisingly, Brie’s acting training included work as a clown for children’s birthday parties while growing up in Pasadena. “I did balloon animals. I did characters. I did these games where you’d bring a ball and a parachute and a boom box and dance around. I was a super­-fun clown,” she says. Then she attended the California Institute of the Arts, an experience she detailed in a widely blogged-about essay, about having sex with her best friend to determine whether he was really gay, for the 2010 book Worst Laid Plans: When Bad Sex Happens to Good People. “We still laugh about it,” she says. “He was like, ‘I never attempted sex with another woman ever again.’ And I was like, ‘You’re welcome.’ ”

Before she landed her part on Mad Men, Brie, 29, spent “three years being a total loser,” living at home and working as a receptionist at yoga studios. She moved into her own place a year ago, but even now the going’s not easy. Mad Men’s current fifth season was preceded by an unusually long hiatus and difficult contract negotiations between AMC and series creator Matthew Weiner that, for a time, left the show’s future in doubt. And Community’s third season came to a screeching halt last fall when NBC temporarily removed the series from its schedule. As Brie puts it, “I’ve cornered the market on shows that not many people watch, but the people that watch them love them intensely.”

Because of the delays, her two shows shot simultaneously, so Brie would sometimes have to run between both sets in the same day. “That’s when I’m most excited and feel like it’s all happening, you know what I mean?” she says. “I liked shooting at Mad Men and then going over to Community and literally taking my hair down. Because Community really feels like the parents are gone and we’re all just having crazy sleepovers and making blanket forts.”

Apart from a small role as a murder victim in Scream 4, Brie’s double shifts on TV have mostly kept her too busy to do movies. The Five-Year Engagement features, by far, her most prominent big-screen role. For the film, she had to learn to do a British accent by “stalking Emily Blunt like a psychopath and just standing near her and mumbling whatever she was saying.” She was so convincing that producer Judd Apatow didn’t realize she wasn’t English until someone pointed it out. “I was shocked, because I love her on Mad Men and I didn’t even make the connection,” he says.

Our shopping trip takes us down Broadway to Madewell, where Brie grabs a patchwork strapless bathing suit off a rack, promising, “If it’s awesome, I’m going to make you look at me in it! And it’s going to be awkward!” (It isn’t and she doesn’t.) Whenever she worries she’s taking too long in a dressing room, she shouts out, “Powering through! Powering through!” She ends up buying another see-through top.

Before that—attention, foot fetishists—she’d spent a good fifteen minutes agonizing over $10 packages of socks at Uniqlo. “All right. I realize you may not think this is the most important decision, but I’m not done looking at socks. Don’t be mad. I need another minute,” she said. “One’s striped and one is textured. Which one do I like more? I don’t know!” She picked both, then muttered, “What have I done?”

Watch Alison Brie and Community Castmates Play Pop-Culture Trivia