‘This Is 40′: Mom and wife Leslie Mann simmers in husband Judd Apatow’s latest

Leslie Mann humorously unpacks her marriage to writer-director Judd Apatow in their fifth film together, "This Is 40." Mann plays Debbie, a wife who turns 40 and watches her marriage to Pete (Paul Rudd) sag while their daughters (Maude and Iris Apatow) observe -- and comment. "It's a weird time," Mann told Yahoo! about turning the big four-oh. "It's like, not everything is in front of you anymore. It seems like one day we're bawling our eyes, and the next day it's fine."

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Thelma Adams: You did a brave, brave thing in this movie. You enter a room where your husband is lying on the bed working and try to seduce him. You even expose one breast and he still doesn't get the message: You want whoopee. Ouch!

Leslie Mann: I wanted to show how that feels, to feel unwanted or feel undesirable. It's awful. I felt like having a part of a boob hanging out would make her more vulnerable and would make it hurt even more when she was rejected. That was my idea, not Judd's. I didn't do it just to show boob.

TA: And you do have some steep competition in this movie with 26-year-old Megan Fox appearing in a pushup bra. You even have an exchange where you touch her breasts in a boutique dressing room to see if they're fakes, and she says, "I'm just young."

LM: She just has great boobs. Better boobs than I've ever seen in my life. That scene was in the script. It wasn't something we improvised. I'm very protective of younger actresses, because it was so hard for me coming up in the business. I wanted to get that scene over with as quickly as possible and get our shirts back on.

TA: Moving on from sexy to silly, Albert Brooks plays your father-in-law in the movie. It's so crazy that his character has a second family with triplet toddler boys that he can't tell apart, and so true in our age of remarriage.

LM: Isn't he great? One of my favorite movies was "Broadcast News," by Jim Brooks. Remember that scene in "Broadcast News" when Albert is reading the news and sweating? It's so hilarious and heartbreaking at the same time. When I worked with him, he was getting into his part as Pete's father and I was getting into mine, and there was some friction. Not in a bad way, but we were committed to these characters that were at odds with each other. Now, we see each other and he's back to being one of the greatest actors ever.

TA: This movie is clearly close to Judd's heart, but how close is it to your actual family?

LM: It is emotionally truthful, but it is a fictional story. It isn't an extension of my marriage, because that would be a lie.

TA: So what's it like collaborating so closely with your husband of 15 years?

LM: All at once, all the time: conflict, challenge, joy. We're both very passionate and trying so hard to do the best job that we possibly can. It gets really intense. We yell at each other. We want to kill each other, and we're laughing at each other. We're happy with what we've done, then unhappy. It's a tornado of every emotion happening at once all the time. It's never just one or the other. It's madness.

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TA: And what about including your own daughters in an R-rated comedy?

LM: I love the idea of the girls being able to express themselves creatively and being heard. Maude and Iris are really interesting and smart. It's so rare that kids get listened to in that way, and they really believe in themselves. I didn't have that as a kid.

TA: Did you have any misgivings about casting your daughters?

LM: I didn't want to do it at first, because I didn't think it was a good idea. Child actors don't have a very good track record. The first couple of movies we did with them, they had no idea what they had done, since they couldn't see the movies and their friends couldn't either. It was just hanging out with Mom and Dad and their friends at work.

TA: How has that changed with this movie?

LM: This time Maude's a little older, and she gets it. She seems interested. It's funny to watch Iris be so funny, and also to watch Maude do emotional scenes. I'm very proud, but also I really want them to be at school and do well on their math homework. I don't want them to have the pressure of being in this world at their age. It would be too much. I can't even handle it!

See the trailer for 'This Is 40':

'This Is 40' Theatrical Trailer 2