Charlize Theron was hospitalised for five days after watching the comedy film Borat because she had "laughed so hard."

The 43-year-old actress, who is currently starring in Long Shot opposite Seth Rogen, has revealed that while watching Sacha Baron Cohen's 2006 comedy with a pre-existing neck condition, she laughed so much her ''neck locked up''.

Speaking on Late Night with Seth Meyers she said, ''I went to go see Borat I had a pre-existing injury in my neck - a herniated disk in my neck.

"A few of us went to go ... and halfway through that movie, I laughed so hard that my neck locked up. And, like, an ambulance had to take me to the hospital, and I was in the hospital for five days.

"I didn't finish the movie! I've never, like, fully finished the movie. It's a risk now!''

During the interview, Theron  also recalled a gift given to her by her friend Rihanna, with whom she shares a publicist.

Theron revealed how the singer gave her a T-shirt with a birthday greeting from their publicist Amanda Silverman on the front, which stated Rihanna was her ''favourite client ever''.

''A couple of months ago I got something in the mail, it was a T-shirt. Rihanna had made a T-shirt of the birthday greeting that my publicist gave her which literally was like, 'To my most favourite client ever.'

"And Rihanna wrote in the following email, 'I'm making a T-shirt of this and sending it to Charlize.'"

Theron recently opened up about raising her first child Jackson as a girl, after first introducing her to the world as a boy.

Long Shot is in cinemas now.

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