The lead role in the political comedy Our Brand Is Crisis was originally going to be played by one of the film's producers, George Clooney. When he dropped out, another producer stepped in: Sandra Bullock. Yes, the screenplay was revamped to change the gender of the character.

Billy Bob Thornton and Sandra Bullock in Our Brand Is CrisisSandra Bullock explores corporation corruption in 'Our Brand Is Crisis'

And Bullock loved playing her, even with the dark subtext. "What we show in the film is happening now for real - the backstabbing, the political chicanery and the rest," she says. "It happens every day, but not just in America and not just in politics. Every big business has its spin doctors, attorneys and manipulators, including the dark ones they never talk about who go in, fix and destroy things and then clean up the mess afterward. It's everywhere. Wherever there's money and power involved, you have levels of this happening."

Watch the trailer for 'Our Brand Is Crisis' here:

In the film, Bullock plays a political publicist trying to export US-style campaigning to a South American country. And she said it just confirmed how wrong the system is. "We knew it was like this before we made the film. That's the sad part. This was evident to us years ago," she says. "Once you see behind the curtain, so to speak, you can't un-see it. Our goal here was to create a fun commentary on the absurdity of it. After all, it is the theatre of the absurd! The win is all-important, which is kind of sad, because it's often about winning at all costs. It doesn't matter what culture it decimates. It doesn't matter which people it harms. It's all about the win, period."

More: Sandra Bullock opens up about working with David Gordon Green

And like her character, the 51-year-old actress is effortlessly batting away questions about a scene in which she moons colleague Billy Bob Thornton through a window. "I'm freakishly modest," she laughs, "but for some reason that day I was just dropping trou and hanging it out the window, not even thinking who's on the other side to see that mess. It was just ugly."