The notoriously reserved Keira Knightley, 29, covers Elle UK's July 2014 issue, in which she dishes about her close circle of friends, including her Atonement co-star Benedict Cumberbatch.
Just how close are the two?
Apparently, Benedict once "joke-punched" a journalist in the face for dissing Keira.
Video: Adam Levine & Keira Knightley Reveal Jitters of Performing in 'Begin Again'
"When I saw him again, I said, 'Did you punch a journalist?' and he was like, ‘I f*cking did,'" Keira recalls to the magazine with a grin. "Everybody needs a friend like that."
Though one thing the pals probably won't be doing together?
"I hate karaoke. Like, I really, really hate it. I have to be so drunk I’m nearly about to fall down before I sing in front of anybody. It just terrifies me," she admits. "But, also, among the people you go with, there will be somebody who secretly has an amazing voice, and you're just like, 'F*ck off.'"
The beautiful actress also admits to having surprising insecurities when it comes to being out and about in public.
"I know I can be very … I have an on/off switch and, when I’m doing publicity, I'm absolutely OK, but when I'm not working and people come up to me, I've not got the head on to handle that," she admits. "I don't give off a nice energy and that makes me still feel awkward. I think it's dreams and fantasies. People want you to be a specific kind of person and if, in the flesh, you're not, that can be tremendously disappointing."
As for the stylish star making headlines for recycling a Chanel dress she's already worn for her wedding to husband James Righton, the explanation is simple.
"Every time I've worn that dress, I've had a fantastic night, and if you've got a dress where you've always had a fantastic night, it's worth having another fantastic night in it," she says.
Related: Keira Knightley Re-Wears Her Wedding Style
Keira can next be seen in Begin Again opposite Mark Ruffalo, out July 4.