If you squirm when you’re watching TV with your parents and a sex scene comes on, spare a thought for Jamie Morton.

In retirement Morton’s dad caught onto the success of what he calls 50 Colours of Grey and, under the pen-name Rocky Flintstone, wrote an erotic novel called Belinda Blinked. It’s about sales rep Belinda Blumenthal’s adventures in the implausibly sexy world of the pots and pans industry. Then he gave his manuscript to his son.

That text is now the basis for My Dad Wrote a Porno, a podcast launched in 2015 by Morton and two friends, Alice Levine and James Cooper. They join Morton as he reads Belinda Blinked aloud – children’s-story-time style – and work through what Morton has described as the “eye-watering imagery” (“Her tits hung freely, like pomegranates.”) written by his father. Their reactions and commentary (often just gasps and hand-in-head moans of “noooooo!”) are spontaneous – they hear the story unfold at the same time listeners do. It has been downloaded 50 million times.

“When he [Jamie] first brought it to us we just fell in love with it straight away,” says Levine of the original manuscript. “We took hours and hours to read even just the short amount we had – about three chapters at that point.”

Part of the appeal is that Morton is reading erotica written by his own father, which “is obviously so excruciating for him”, says Levine. But also entertaining is Flintstone’s ineptitude as a writer (some of Flintstone’s sexy scenarios are more Twister than tryst) and his fundamental misunderstanding of anatomy. At one point a character grabs another’s cervix.

“Another bit is about someone’s nipples being like the ‘three-inch rivets that held together the whole of the fateful Titanic’,” says Levine. “I mean, I cannot think of anything less sexy. You’re talking about probably the most famous tragedy ever.”

I ask Levine if anything Flintstone comes up with still shocks her. “Are you joking? All the time! In the world of sitting around the table with them [Morton and Copper] I’m more open, but really, I blush so easily. Some of the stuff Rocky comes up with I’m like, ‘Really? Is that a thing?’ I guess now I know the depths Rocky Flintstone’s mind can go to, but I’m definitely still taken aback.”

Often the trio get barely three or four words into a reading before the analysis begins or they descend into howls of disgust or chortles of disbelief, such as when Flintstone writes: “Her vaginal lids popped.”

But Levine loves most the moments when Flintstone shines through as the daggy dad that he is and “forgets he’s supposed to be writing erotica”, says Levine. “In a Christmas special there was a whole bit about how to microwave some mulled wine. It’s so pedestrian and so basic. And I just love it.” He’s also dedicated much of a chapter to how hard it is to book a taxi.

If all of this comes across as three mates laughing at an in-joke, it’s not like that. The podcast doesn’t rely on taking cheap shots at Flintstone for its humour. The three broadcasters approach the core text without cynicism – there’s nothing of the cool kids ganging up. There’s mortification, sure, but most of that is reserved for Morton, Flintstone’s son. The show has a big heart and its presenters approach their task with affection. It’s part of what makes it so funny.

“We love the book,” says Levine. “It brings us so much joy. And we’re being a bit juvenile by picking it apart and laughing at various anatomical errors, but often we’re the butt of the joke because James doesn’t get something or Jamie’s feeling squeamish or I’m a prude.”

The My Dad Wrote a Porno live show was a hit in London and is coming to Australia. As well as audience participation it will include a new chapter of Belinda Blinked.

There are more books in the Belinda Blinked series to come, too (“To be honest, we can’t stop Rocky. He’s a runaway writing machine”). The podcast is currently up to season two – each covers one book in the series – and a physical book, annotated by Morton, Levine and Cooper (with all spelling, punctuation and grammatical errors in tact), has been published.

How does Rocky Flintstone feel about it?

“He gave it to a lot of people for Christmas, so that’s a good sign,” says Levine.

Buy tickets.

Tour dates:

Melbourne
Thu August 17 – Hamer Hall
Fri August 18 – The Athenaeum (sold out)

Sydney
Sat August 19 – Sydney Opera House (sold out)
Sun August 20 – Sydney Opera House

Brisbane
Mon August 21 – The Tivoli

Adelaide
Wed August 23 – Her Majesty’s Theatre

Perth
Thu August 24 – Astor Theatre