Ashton Kutcher has said he's happy to strip off on screen.
The actor reveals more than he expected in No Strings Attached in one scene, where he wore only a towel to cover his man bits.
"I like having it out, I don't mind being naked - we all came into the world this way, and there's very little you can do about it. You are who you are," he said.
Ashton added: "The towel was smaller than I thought! It was the smallest towel we could get and still cover things up."
Ashton didn't opt for a 'body double' either.
"It's CGI... with a lift and a little reshaping and the wide-screen really does something. It makes it one big a**," he joked.
While he may be fine with baring all, there's no denying filming the sex scenes with a semi-naked Portman were "infinitely awkward".
"You have 40 strangers standing around. It's less awkward for guys because the crews tend to be slightly more masculine," he explained.
"Whenever I'm doing sexual scenes, I stop worrying about myself by making sure the other person is OK. I try to focus on the other person, and then I apologise a lot."
:: No Strings Attached is in cinemas on February 25.