The crew of 'Ted' thought Mila Kunis and Seth Macfarlane were constantly fighting.

The actress and her director have known each other for years after working on animated comedy 'Family Guy' together but Mila admitted their easygoing relationship, where they often shout swear words at each other, worried the cast and crew,

She told Total Film magazine: ''I have never had the kind of shorthand I have with MacFarlane with anybody before. I've never worked with somebody that I've known for 13 years. It took the crew a good solid week to realise that we talk to each other, not the way an actor and director do.

''We're like, 'Hey, what the f**k?' It's very much an honest conversation and the crew thought we were fighting. But he's one of my closest friends and it was an amazing environment.''

Mila, 28, revealed Seth first approached her about her role in 'Ted' four years ago but only to get her advice on which actress to cast.

She said: ''I've known about this movie since I was 24. Seth told me about this character who's in her late twenties, early thirties, asking me which actors I thought would be right for it and four years later The Script was ready and he said 'Why don't you do it?'''