Tribeca 2012: Emily Blunt Gives Her Cookie Monster Impression, Talks 'Five-Year Engagement' and 'Looper' (Video)

Emily Blunt walked radiantly across the red carpet at the Tribeca Film Festival-opening premiere of The Five-Year Engagement on Wednesday; later this year, she may just want to take a nap.

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But first thing's first: the major New York City red carpet. Blunt features in the Judd Apatow-produced, Nick Stoller-directed comedy as Jason Segel's loving fiancee, who, thanks to a series of continuing academic opportunities in Michigan, keeps delaying their dream wedding in their hometown of San Francisco. 

And because she keeps her British accent, co-star Alison Brie, who plays her sister, had to turn her California-native American twang into a more proper, distinguished English voice. Blunt says Brie was a natural -- though she did her best to help.

"She did a really, really good job. It's hard. And she had to do my accent, specifically," Blunt said. "She listened to tapes of me, and I was on set being like, maybe it's tom-ah-to, not tomato. But she has a really good ear. She did it really well."

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Blunt, of course, didn't just get to skate by without having to do her own vocal shifting. There is a scene in the film in which she and Brie turn their respective British accents into Muppet voices -- Brie as Elmo, and Blunt as Cookie Monster. Blunt called it "surprisingly easy," and to prove it, she gave her best impression to THR in a video you can view below.

Later this year, Blunt will feature in the Rian Johnson-directed time travel noir film Looper, which stars Joseph Gordon-Levitt and Bruce Willis as the same person at different points in time. To look more like Willis, Gordon-Levitt wore plenty of prosthetic makeup, which Blunt says threw her for, well, a loop.

"I only got to see him as himself in the evening, when the prosthetics were off," she remembered. "I remember the first time I met him, he was wearing the prosthetics and I was very confused. So I remember looking at him and saying, I know that's Joseph Gordon-Levitt, but I know that's not his chin... it was very jarring."

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Much more immediately, however, she will on Thursday night walk the red carpet once again for her much more low budget and improv-based dramedy Your Sister's Sister, co-starring Mark Duplass and Rosemarie DeWitt and directed by Lynn Shelton, who is best known to this point for her work with Duplass on Humpday.

"We shot it in twelve days, it was made for no money and it's sort of a love triangle, it's really funny and really fresh," Blunt enthused. "It was fantastic and it was quite a lot of pressure to do an improvised film and it was exciting because you had that responsibility to write as you were acting."