Chris Hemsworth had to model a range of prosthetic penises for his new movie.

The writers and co-producers behind adventure comedy 'Vacation', John Francis Daley and Jonathan M. Goldstein, have revealed one scene required the hunk to walk around wearing tight underwear stuffed with the fake member, which was preceded by a strange meeting where he tried several on for size.

Jonathan explained: ''We went to a room with him and he modelled a couple of options for us.''

John added: ''It was the weirdest couple of hours.''

However, the 31-year-old actor - who plays a weatherman married to Audrey Griswold (Leslie Mann) in the film - confessed he was left blushing by the bizarre session because he felt ''intimidated'' by the strange situation.

He said: ''It was embarrassing. It was hilarious and probably more for other people than me ... I was intimidated by that set and scene.''

But they eventually agreed the biggest possible representation of his manhood was perfect for the scene.

Chris quipped: ''It's part of character development. We went bold, ya know - big and bold.''

And fellow actor in the movie, Ed Helms, joked he wasn't surprised by the size of the enormous prosthetic because it was based on his own genitals.

He told E! Online: ''I knew exactly how big it would be because it was moulded off of me. That's how we do it, [but] I had no idea his abs would be that amazing. I actually washed my clothes on his abs.''