Eli Roth let loose a ''black satanic goat'' to trash Jack Black's trailer and spook him while they were shooting new movie 'The House with a Clock in Its Walls'.

The 46-year-old director was determined to finish the fantasy thriller on a high so, along with child actor Owen Vaccaro, arranged for a deranged farm animal to be delivered to the comedian's personal space and wreck his belongings for a prank.

Speaking to talkRADIO at the world premiere of the film in London on Wednesday night (05.09.18), Roth said: ''Owen was obsessed with doing a prank. He was like, 'We have to prank Jack, we have to prank Jack.' And I was like, 'Let's put a goat in his trailer, a really black satanic goat.' And he was like, 'How are we going to do that?' And we did it. On the last day - we actually have footage of it that we're going to release - we put it in his trailer and the goat went nuts and started stomping over everything and Jack was like, 'OH MY GOD, IT'S A GOAT!' ''

Owen, 13, has revealed they were deliberating over getting a giraffe or a goat for the prank because the cast - also comprised of Cate Blanchett - were convinced the shooting location was haunted by a long-necked mammal, but, in the end, they opted for the latter because it was easier to get hold of quickly.

Owen explained: ''We put a goat in his trailer and we scared him. The house that we were filming at was haunted by a giraffe - and we also thought it was haunted by a goat - because the person that used to live at the house had a giraffe.''

Jack added: ''We finished my last shot of the whole movie, there was hugs, kisses and tears, I walk back to my trailer, I open the door and staring at me in the face was this evil looking goat. Now goats aren't dangerous animals but of all the non-dangerous animals, goats are the most terrifying because they look like Satan. I let out a little shriek and they captured it on camera and they will rule the day.''

However, the 49-year-old comedian has promised that he will get all those involved back when and if they ever shoot a sequel in the future.

He said: ''Often times at the end of a film there will be a prank pulled on the cast members. And Owen Vaccaro and Eli Roth - those sons of guns - they got me good. And if we ever do a sequel you better believe I'll be getting them back.''