Father knows best

He's a grouchy septuagenarian with a talent for cutting remarks. Now Justin Halpern's dad has become an unlikely star. Lena Corner finds out how

When Justin Halpern got dumped by his girlfriend he found himself, at the ripe old age of 28, on his parents' doorstep begging for his old room back. A fairly commonplace scenario these days maybe, but in the Halperns' case, the whole family got a lot more than they bargained for.

Justin, an aspiring comedy writer, installed himself in the corner of his parents' living room in his "office" and every day, clad only in his pyjamas, sat there trying to carve out a career for himself. He found himself regularly sniggering at the things that came out of his septuagenarian father Samuel's mouth and it soon dawned on him that the most valuable source material he could hope to find was right there under his nose.

"I just started to realise how off-the-wall and funny he was," says Justin. "You know exactly where you stand with him at all times. He is a man who doesn't mince his words."

In August last year Justin posted some of his dad's sayings on a Twitter feed – the perfect format for one-liner musings – and called it Shit My Dad Says. A sample quote from him last November runs: "I don't need more friends. You got friends and all they do is ask you to help them move. I'm old. I'm through moving shit."

Halpern Snr's brutally honest and ever so slightly bilious world-view struck a chord. "For the first week a handful of my friends followed it," says Justin, "then three weeks in I woke up to find I had a thousand followers, then the next day it was 10,000 and the day after that 100,000." The numbers continued to spiral and today they stand at 1.4 million. Justin is now working with the makers of Will and Grace to turn it into a TV pilot for CBS and it has also finally made it into print with the publication of the book Shit My Dad Says, out this month.

"I had absolutely no idea any of this would happen," says Justin. "I really thought the only people interested would be my friends because they know my dad and no one else would care," says Justin. "I guess people just really like its honesty."

Essentially what Justin has done is take the age-old father/son relationship story, spun it across various media and found a uniquely modern way of sharing it. The book picks up where the Twitter feed leaves off, fleshing out his dad's tale further. We find out that Halpern Snr lives in San Diego and is a doctor of nuclear medicine who grew up on a farm in Kentucky, served in Vietnam and lost his first wife to cancer. And we get to know Justin's mum, who is a lawyer of Italian descent, his two brothers Dan and Evan, his adopted brother José, as well as various dogs.

We also discover that as a child Justin often felt scared of his dad. "When I was little I mostly felt terrified of him, I couldn't appreciate that I was dealing with the least passive-aggressive human being on the planet," he says. On Justin's first day of kindergarten, for example, where some parents might fuss and mollycoddle, Halpern Snr simply said: "You thought it was hard? If kindergarten is busting your ass, I got some bad news for you about the rest of your life."

As Justin grows up the book captures the awkward formative moments between father and son – the hangovers, the first break-up and the "sex education" that consisted of Halpern Snr presenting his son with a pile of condoms. When Justin hit adolescence there was still no let up: "How do I know you're going through puberty?" Halpern Snr barked at him one day. "Oh, I don't know, maybe it's the three hundred dick hairs you suddenly leave all over the toilet seat that clued me in."

"It was tough because puberty is tough anyway," admits Justin. "It's a little tougher when you're going through it with someone who doesn't hold back. I felt very self-conscious."

Despite this tough love, a sense of deep fondness runs all the way through and ultimately it's the story of a father trying to teach his son right from wrong and bring him up in the best way he can. In many ways Halpern Snr is the voice of reason in a world where we spend too much time pussyfooting around, fearful of creating offence.

Nowadays Justin is grateful to his dad and not just for providing him with endless comic fodder. "When I got older did I come to understand a bit better where he was coming from," he says. "He has definitely given me a thick skin. He brought me up totally prepared for life to give me an ass-kicking and when it did I took it and managed to bounce back."

At first Justin kept his project secret from his dad, but once publishers and TV studios came knocking, he realised he had to tell him. After expressing incredulity that his own son was capable of writing a book, it's clear that Halpern Snr is enormously proud of what his son has achieved, though he still refuses to buy the book. "Your mom just ordered 35 copies of your book. I'm not paying for one. Fucking. Copy. Mine's free."

True to form, Halpern Snr simply doesn't dwell on what people think of him and has also threatened to shoot any reporters who go anywhere near him. I ask if all the publicity has turned their relationship a little self-conscious with Halpern Snr honing his one-liners ready for Twitter. "He isn't internet savvy, he never even looks at it, he really doesn't care," says Justin. "Plus he can't edit himself. He's been the same for 70 years. He's not going to change now."

Shit My Dad Says is published by Boxtree, £11.99

'Stuff' his dad says

On parenting

"A parent's only as good as their dumbest kid. If one wins a Nobel Prize and the other gets robbed by a hooker, you failed."

On Justin's girlfriend

"I thought she'd have bigger breasts. I'm just being honest. That's not a bad thing or a good thing. That's just a thing I thought."

On celebrity

"Who is this woman? Kate Beckinsale. Well you can tell Kate Beckinsale she sucks."

On technology

"Why would I want to check my voicemail on my cell phone? People want to call me, call again. If I want to talk to you, I'll answer."

On dogs

"The dog is not bored. It's not like he's waiting for me to give him a fucking Rubik's Cube. He's a goddamned dog."

On paying parking tickets

"Pay the parking ticket. Don't be so outraged. You're not a freedom fighter in a civil rights movement. You double parked."

On child rearing

"Your brother brought his baby over. He told me it could stand. It couldn't stand for shit. Just sat there. Big let down."

"The baby will talk when he talks. It ain't like he knows the cure for cancer and ain't spitting it out."

On food

"I didn't live to be 73 years old so I could eat kale. Don't fix me your breakfast and pretend you're fixing mine."

"Anytime someone sells you food in a sack, it's not a sack of food, it's a sack of shit."

"I'm sitting in one of those TGI Friday's places, and everyone looks like they want to shove a shotgun in their mouth."

On health

"A scar ain't 13 goddamned stitches. I'll introduce you to men with REAL scars, then we'll all laugh at your fucking 13 stitches together."

"Can we talk later? The news is on ... Well, if you have tuberculosis it's not gonna get any worse in the next 30 minutes, Jesus."

On possessions

"You're being fucking dramatic. You own a TV and an air mattress. That's not exactly what I'd call 'a lot to lose'."