The Battleship star wanted to know why all her friends were talking about the bestseller and picked up the book to read on a flight to South Korea - but she was carded at the check-out.
She explains, "I was like, 'Is there something wrong?' and she (check-out girl) said, 'No, it's for this book'.
"I was like, 'What am I getting myself into...?' You have to be 18 - and you should be 18 because I open it up on the plane and there is no way I would have my 18-year-old child reading this book. It is crazy, wild.
"It's really inappropriate... She (James) talks about butt clamps... I haven't finished it yet. I can't continue."
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