Why is it so weird to see Tina Fey and Amy Poehler swear?

Sisters, the Fey-Poehler comedy that took third place at the box office last weekend with $13.4 million, is filled with a wide range of expletives and explicit descriptions of sex. But that shouldn't be shocking - Fey, a producer of the movie, has a pretty dark sense of humor. Poehler doesn't hold back. Neither does the movie's screenwriter, Paula Pell, a longtime Saturday Night Live writer who also helped punch up Bridesmaids.

The dirty language becomes a talking point about the film that one site dubbed "surprisingly raunchy" - it's a topic that comes up in interviews and reviews. "You're kind of a hall-of-fame curser in this movie," Matt Lauer noted when Fey stopped by the Today show last week. "We're talking construction-site-level cursing."

"Probably more cursing than you've had in your entire career," weatherman Al Roker added.

"That you've seen on camera," Fey shot back. As she explained in other interviews, she swears quite a bit in real life. She told Lauer all the cursing in the movie came so naturally to her it "was like an old swaddling blanket."

Is the swearing notable because two actresses who have spent their careers adhering to the strict guidelines of broadcast television (30 Rock, Parks and Recreation, Saturday Night Live) can suddenly let R-rated language fly? That's Fey's theory.

"It's like a privilege to curse," Fey told the New York Daily News. "Amy and I both worked in broadcast TV for so long, so yeah, it was fun to let it rip a little bit."

In that same story, the Daily News referred to the script as having "profanity-laced dialogue - so sexually charged that it would make Amy Schumer blush." With Schumer recently saying she thinks she's labeled a "sex comic" because she's a woman ("I feel like a guy could get up here and literally pull his [genitalia] out, and everyone would be like, 'He's a thinker!' "), that line seems especially gender-specific. The gender aspect also made its way into reviews, such as Parade magazine's take on the movie's raunchiness: "Somehow, grown-up jokes Christmas-gift-wrapped by these two smart, classy leading ladies make the dirty seem merely naughty."

Or the New York Post with a less-loving critique, implying the language was distracting: "Its gleefully dirty dialogue makes Sisters a livelier outing, even if neither actress sounds totally comfortable working this blue"; the reviewer added a list of their fellow female comics: "I'd love to see what raunch-friendlier comics like Amy Schumer, Wanda Sykes, Jenny Slate, Melissa McCarthy, or the Broad City broads could do with Pell's material."

At the same time, Fey reminded viewers that even though, yes, two broadcast TV actresses were seen cursing quite a bit, there was more of a point than to just shock.

"We definitely wanted to make sure there were jokes beyond just cursing and being dirty," Fey said. "But I'm not going to lie. I curse a fair amount in real life - not in front of my children - but I'm pretty good at it."