PUT comedian Will Ferrell and Prime Minister Julia Gillard in an interview together and things were always going to get interesting.

The American funnyman was a guest on Channel 10's The Project and came out swinging when he acted confused over how to address the Prime Minister when she appeared for an interview via video link.

"Ah Miss, Mrs Prime Minister?," Ferrell said.

"Uh, whatever," she replied.

"Can I just call you Jules?," he said.

"That'll do, too," she said.

Ferrell had the audience and Ms Gillard laughing with his first question about her partner, Tim Mathieson.

"I have a question for you. I understand your partner is a hairdresser, is that correct?," he said.

"Yes he is," she replied.

"I suffer from horrible split ends, would you have any advice for me because this hair's terrible, it's like horse hair and I'm at my wits end," he said.

Ms Gillard took Ferrell's comments in her stride and advised Ferrell to stock up on hair products.

"Will I can give you some very clear advice, and I'm sure Tim would endorse it. You need to get yourself to a hairdresser straight away, then spend buckets and buckets of money on in-salon treatments, you need to buy everything that they recommend for you to take home," she said.

The banter continued when Ferrell asked another question on a topic Gillard had already been asked about.

"Julia, it's Will again. I'm wondering do you have an opinion on the power prices?...Did someone already ask about that?," he said.

"Will, someone did already ask me about that. I'm concerned with all these treatments in the hairdressers there's a lot of power being used with blow dryers and the like, so these power price issues are important for you too."

After the interview, Ferrell, who stars in The Campaign, in which he plays an American politician in a presidential race, was asked if he had any advice for Ms Gillard.

"I don't. I wish her the best of luck," he said.

But he did give some tips about attacking the opponent.

"She should just research any sort of superficial fact about the opponent and just hammer away without any sort of conscience whatsoever, because in the end it really won't matter."

Originally published as Stay classy! Gillard v Will Ferrell