Everytime somebody goes "I don't think we can do that", we want to do it 
Along with his younger brother Peter, Bobby Farrelly is the man behind some of the most groundbreaking gross-out comedies of the 1990s - from Dumb & Dumber to There's Something About Mary and Me, Myself And Irene. The brothers' latest movie is Stuck On You, a comedy about a pair of conjoined twins, played by Matt Damon and Greg Kinnear.
Where did the idea for the screenplay come from?
A story we read about some real life girls who were conjoined. We were really fascinated by the fact that they were trying to lead separate lives. One wanted to be an actress but the other one didn't. Yet they would each accept whatever the other one wanted to do because they knew that they had to go through life like this and they didn't want to be the buzz killer for the other one.
You always work with your brother Peter. Do you sometimes feel stuck together?
We don't ever feel like, "Oh boy, I'm stuck on him, I can't ever get away from him." We're more like the two guys in the story. They are stuck together but they never think it's a terrible disadvantage. They think it's working out great and they've got the world by the tail. I think that's how we are. We are together... but things are good!
You seem to like putting A-list stars in compromising positions...
It's a risk thing. Everytime somebody goes "I don't think we can do that", we want to do it. The biggest laughs are always those that have something going off in the back of your head going, "This is very risky!"
Was there anything like that on this film?
There was a little bit about that with Cher's character. She's poking such fun at herself and her image that she's carefully cultivated for over 30 years that there's a risk to her to do that. But to make really good comedy you have to be brave.
Were you brainstorming lots of different combinations of actors for the lead?
Yeah, for years and years. It just never felt like we had the right one.
What's the most unlikely combination you had?
There was a point when we wanted to do it with Jim Carrey, just because we like him so much. But we couldn't figure out who we could put next to him who wouldn't seem the weaker of the two. We wanted them to be a 50-50 team, and so we had to find somebody who could match Jim. Someone said, "How about Woody Allen?" Suddenly, it all fell into place! Jim's got the whole liver, Woody's ageing two to three times faster than him!
Did you speak to Woody Allen about it?
Yeah, he was really keen. But things just didn't work out. That's the way casting goes. You just sort of open your arms up and hope it comes to you.
