Hugh Jackman is still brimming with enthusiasm for his impressively sideburned alter ego. Photo / AP

Hugh Jackman says it was his idea to strip off for the new X-Men movie.

The hulky star - who is playing mutant Wolverine for the seventh time in the latest film - is shown in one scene getting out of bed, naked from behind.

But instead of fretting about going nude, Jackman said he told director Bryan Singer the scene wouldn't work if he was wearing boxers or briefs.

"It was my idea. Bryan came up to me and said what do you think, boxers or briefs?" he told KIIS FM. "I was like, Wolverine's in bed with a woman."

"He's not wearing boxers or briefs - (he's) commando."

He also revealed he had to wear a bright green sock on a part of his anatomy that wasn't a foot so special effects artists could erase any threats to the film's PG-13 rating."It's really hard to hide that thing," he joked.

Co-star Jennifer Lawrence was similarly relaxed about wearing little more than a coating of blue paint for her role as the shape-shifting Mystique, he added. "She's very confident, and why wouldn't you be?" he said.

Praising the Oscar-winning actress for her down-to-earth attitude, Jackman said Lawrence had even won his son over after a trip to a local theme park.

He said Lawrence crashed the excursion after overhearing father and son planning a rollercoaster ride. "She's pretty cool that girl," Jackman said his son resolved.

- AAP