Julia Roberts has revealed her face goes red whenever she swears on screen.
The Oscar-winning actress got to blurt out some expletives in August: Osage County, where she plays resentful daughter Barbara Fordham opposite Meryl Streep's troubled matriarch, Violet Weston.
"It's like Erin Brockovich all over again," she said. "I remember doing Erin Brockovich and (director Steven) Soderbergh coming to me saying, 'You would be more convincing if your face didn't turn bright red every time you curse'."
Julia heaped praise on her co-star Meryl, saying she was the reason why she signed on.
"She is the best there is. She is really phenomenal," she said.
"To watch her up close doing that thing, that I, like everyone, have only sat in the dark and watched in awe of. Where does it come from? How does she think of this stuff? To get to watch that up close and to see her be a real life person, actually working really hard to be that great, it was a privilege."
She admitted to having concerns about a scene where she strangles Meryl, as tension between mother and daughter build.
"The fight was not exactly part of my dream of working with Meryl - she's really strong!" she said.
"I just thought we would sit around and talk about being unique and inspiring, but there I was on top of her. She was very strong and had a lot of sweet patience with all of us."
:: August: Osage County is in cinemas now.