Dwayne Johnson wore a beard made of testicle hair for 'Hercules'.

The 42-year-old star - also known by his wrestling name ''The Rock'' - stars as the Greek hero in the upcoming film of the same name and he's confessed he was shocked to find out what parts of his costume had been made out of.

Speaking on 'Live! with Kelly and Michael', he said: ''The beard hair, I've got to mention this, this is crazy. The beard wasn't lace so it had to be put on strips cut in tri, quarter inch wide, piece-by-piece.

''So I asked my Italian designer, 'Matteo what is this?' And he goes, 'Oh, it's the hair from a yak'. It's very expensive and very fine hair and I said, 'Yak?' And he says, 'Yes, yak'. And he's putting it on my face like this [rubs the area around his mouth] and I say, 'What part?' And he goes, 'The testicles'.

''It's the commitment of which I will go to.''

The 'Pain & Gain' actor - whose usual hairstyle is that of a shaved head - has long flowing locks in the movie and he's revealed it took nearly four hours to put the wig on every day on set.

He explained: ''It's a system, it's a process, it's an experience. Everyday for five months. Every day, three and a half hours, every day.

''Three and a half hours every morning. So I would get up at half three and then I would eat and train again, as I had to train twice a day for the role, and then I would go and sit in hair and make up for three and a half hours for the transformation.''