30-year-old "Ugly Truth" star, Katherine Heigl goes full-on screen siren in an asymmetrical Roberto Cavalli gown for the August cover of InStyle magazine.

On her new film, Heigl tells the fashion tome that she's "really glad ['Ugly Truth' is rated] R."

"I didn't want to do another PG-13 movie. [In any real-life contentious relationship with romantic underpinnings] you're probably going to drop the F-bomb once in a while."

"You're probably going to say some things that are kind of harsh. And you're definitely going to talk about sex. It doesn't have to be so Snow
White and Prince Charming."

And don't think she'll backtrack if people don't like what she says. "Now I've got this moniker that I'm the foot-in-mouth gal, and I keep thinking, in what way?" she says.

"Because I said something you don't agree with? Because I said something you don't like? I'm just telling you my opinion. I hate the idea that I can't be honest about how I feel about things because it's going to piss somebody off who feels differently. That seems preposterous to me."

She even stands her ground when it comes to beauty, "Sometimes I'll wear dark nail polish, but [my husband] Josh doesn't like it. That's just gonna have to be too bad."

Read more of Katherine Heigl's InStyle interview here.

The August issue of InStyle hits newsstands July 17.