Jack Black stunned his co-stars on the set of Tropic Thunder by constantly walking around in his underwear.

The actor did have to strip for some of the film's scenes, but also liked to stay half-naked during takes.

Co-star Ben Stiller tells British radio station Heart Fm, "He always takes his pants off, if he sees the comedic potential then those bad boys come right off.

"He's so much more than just a guy who takes his pants off, but he really does that better than anyone else. and he has a great legs and great body.

"He's really comfortable in his own skin so he was more than happy to spend a lot of the movie in barely anything other than his underpants." (c) WENN