Louis CK is driving down the highway to New York and all hell has broken out in the back of his car. 'You have your own water, Kitty, why do you want your sister's?' he says to his daughters, doing his best to sound calm. 'Why are we having a conflict for no reason? It just doesn't seem right.'

The girls, Kitty and Mary, aged 3 and 6, are on their way back to their home in New York's trendy Soho after a visit to see their granny, aunty and cousins, before CK catches a flight to Dublin where he is doing several stand-up gigs before going on to London and the Edinburgh Fringe.

'What is happening in this car is like what is happening in the world with food and oil just now,' says CK, doing his best to ignore the drama unfolding in the back of the car and talking on his hands-free cell phone. 'We hear all these reports that there is a world food shortage or that oil is running out. There is enough to go round but people like to come up with reasons to have conflict.'

Next, the high-pitched noise of a little girl crying fills the car. Mary has decided she needs to pee, and there's not a service station or restaurant in sight. 'There's nothing I can do right now,' says CK. 'But as soon as I see a place we can stop, I will. OK?'

There's silence followed by a muffled sob that gets gradually louder.

Such mundane domestic dramas form the basis of the US comedian's live stand-up shows, which have evolved since he started out doing open-mic spots in Boston 20 years ago to reflect his new status as a 40-year-old father of two. His routines and rants often mine his personal life in uncomfortably close detail, creating raw comedy out of everyday self-loathing. 'The older you get the closer your comedy gets to real life,' he says. 'I don't try to think of funny stuff to say now, I do honest stuff, stuff I think about in real life that most people wouldn't want to share with anyone, let alone tell the world. Then I work on it to make it funny.

'I look at the business of being a parent, eating lots of toxic food to stay sane and drinking a lot when they're not looking.' He also explores race, religion, ageing and coming to terms with his man boobs ('the only thing that a 12-year-old girl and a 40-year-old man have in common').

One of his most popular sketches on YouTube is about trying to find a quiet corner to masturbate in the family home he shares with his wife and children. Is anything off limits? 'There was one time . . . my wife banned one thing but it wasn't about her. Let's leave it at that.' Does she enjoy his show? 'No.'

Though relatively unknown in the UK, the Washington-born comedian is one of the most in-demand comedians in America where he's a regular fixture on TV and the stand-up scene. His profile could be about to go stellar in the UK, too, thanks to his new best friend Ricky Gervais. CK's promotional posters feature a quote from Gervais who declares him 'The funniest stand-up working America.'

The two became friends after Gervais saw CK on YouTube and got in touch to ask him to star in his Hollywood directorial debut, This Side of the Truth which also stars Jennifer Garner and Rob Lowe. CK plays Gervais' best friend, a role that started out small but was expanded by Gervais after the two performed together and creative sparks flew.

'It's fantastic. I saw the British Office and loved it,' says CK. 'Ricky has said a lot of very flattering stuff about me.'

This isn't his first big screen outing: he can currently be seen in US cinemas alongside Alan Alda in Diminished Capacity, the story of a Chicago journalist (played by Matthew Broderick) who returns to his rural hometown after suffering from memory loss.

But writing and performing comedy is his first love. His many writing credits include The Late Show with David Letterman, Late Night with Conan O'Brien, The Dana Carvey Show and The Chris Rock Show, for which he won an Emmy.

CK is currently devising a sitcom for CBS following the success of his HBO comedy series Lucky Louie, which he co-created and starred in.

Like Lucky Louie, his new show is a comedy about a cash-strapped American family, struggling to get by. 'It's pretty familiar territory for a lot of people. It works better on CBS because everyone has CBS whereas HBO is for rich people who can pay for it.'

Though his material might suggest otherwise, he is clearly a devoted family man and is dreading being apart from his daughters for the best part of a month, when he performs in the UK. 'It's the longest I've been on the road for a very long time,' he says. 'I'm worried. Not about the shows: leaving your comfort zone and doing live shows is a great way to keep your material fresh. But I'm really going to miss the girls. They are on holiday in Italy when I'm in the UK so hopefully I can visit them between shows.

'I have a very romantic idea of what Europe, particularly Edinburgh, will be like. I'm not one of those guys who backpacked through Europe while at school, smoking hash and sleeping with Italian models, so Europe is sort of new and exciting for me.'

He pauses for a moment and, before hanging up the phone to put a stop to WWIII, adds, 'By the end of it I'll be fat, sleeping 14 hours a day and suicidal.'

Louis CK: Chewed Up, Pleasance Courtyard, 556 6550, 15-16 Aug, 10.30pm, £12.50 (£11).