Jack Black terrified of Sean Penn

Funnyman Jack Black will think twice before he signs up to appear alongside intense Sean Penn again - because the Oscar winner terrified him on the set of Dead Man Walking.

Black admits he has never felt so intimidated as the time he worked with Penn, because the actor was constantly raving and seemed to be going mad.

The King Kong star reveals: "He was just very reckless and intimidating. I was a little scared of him. You just didn't know what he was going to do next.

"He would burst into spontaneous psychobabble poetry and the whole room would go silent and (feel) uncomfortable, and no one would know what to say next."

But there was method to Penn's madness when her came to playing a Death Row inmate.

Black adds: "When he was on camera, it was like, 'Holy c**p, this guy is on another planet - he's on planet F**king Great Super Acting."