Arnold Schwarzenegger banned his 'The Last Stand' co-star Johnny Knoxville's 'Jackass'-style pranks on set, because making an action film is serious business.
The 41-year-old star is famed for his outrageous stunts and jokes from his time on MTV show 'Jackass', but the 65-year-old action legend told Johnny he didn't want to experience his jokes while making the movie - which sees Arnold and Johnny appearing as Sheriff Ray Owens and arms collector Lewis Dinkum who must protect their town from drug lord Gabriel Cortez (Eduardo Noriega).
Talking to The Sun newspaper, Arnold said: ''I forbade him. I told him the payback would be very painful. Johnny is used to 'Jackass' films, where the more something goes wrong, and doesn't work, the better.
''I said to him our movie was different and he had to change his attitude. He was really good fun to work with - he brought some good comic relief to the movie.''
However, this isn't a sign of the 'Terminator' star - who was at the movie's premiere in London's Leicester Square last night (22.01.13) - losing his sense of humour.
Wherever Arnold goes he hears his famous big screen catchphrases - sometimes even when he's using the toilet.
He explained: ''I was sitting one day on the toilet and next door I heard a loud fart, then the toilet flushing, then someone spitting and then all of a sudden, 'I'll be back!'
''I thought, 'That figures. In the toilet!' I get quoted in really weird places. I've been to the toilet with presidents and political leaders, with famous actors and athletes, all kinds of people. We hold each other...''
The Hollywood legend - who is the former Governor of California - is amazed his catchphrases have become such a part of popular culture, but he often knows when one will resonate with people.
He said: ''I didn't know, 'I'll be back' would become what it has become. You don't know it's going to be repeated. When I did ['The Terminator'], a guy came up to me in New York asking me to say it exactly the way I say it in the film. I could tell that was a line that would stick.''