Keira Knightley's Burping Nightmare

Keira Knightley's tight costumes in The Duchess made her burp, she has revealed.

The 23-year-old plays Georgiana Cavendish, Duchess of Devonshire, in the period drama -- but the "restrictive" attire caused Keira to experience uncontrollable bouts of gas.

She says, "The corsets were very restrictive. The worst part was after lunch because they don't help your digestion.

"My co-star Hayley Atwell and I were playing ladylike characters but belched all over the place."

Keira also said her mother, playwright Sharman Macdonald, inspired her to appear nude on a magazine cover.

She added, "My mum says, 'When I’m a grandmother I want my nipples tattooed blue so I can show everyone I've led a life.' And that's my equivalent."

Keira -- who was recently named the second highest-earning actress in Hollywood -- recently spoke of her encounter with an abusive fan.

The diminutive star was walking alone close to her London home when she was surprised by a overzealous passerby who tried to speak to her.

Knightley admits she was thinking of future film projects at the time and was shocked by the man shouting her name.

But, when the actress failed to respond to her name being called, the fan became aggressive - calling her a "c**t".

And the star was left feeling "jumpy" by the unexpected taunt.

She says, "The other day I was walking down the street and was really thinking about this book I'd been sent. You know when you're really in another place. Somebody jumped out and went, 'Keira Knightley!'

"I got such a shock, I couldn't say anything because I'd been thinking about the book and this guy took incredible offence and started hurling the most amazing abuse.

"He said, 'Who the f**k do you think you are? You're such a c**t.' All this, and I'm completely on my own."

And the star is finding it hard to recover from the encounter.

She adds, "It's weird thing to have to deal with, not on a day-to-day basis, but it's happened enough to make me quite jumpy."