Maggie Muff is a dog-rough tart-with-a-heart whose potty mouth and graphic re-enactments of mechanical sex-acts have left her audiences helpless with laughter.
A cross between brassy factory girl Beth from Coronation Street and one of Viz comic's Fat Slags, the heroine of Dirty Dancin' In Le Shebeen is a promiscuous, binge-drinking, coarse, luridly dressed loud-mouth who is fixated with her "hoo-hoo" – and you can't help liking her.
"He was two sandwiches short of a picnic, but he had a bulge in his trunks like a crusty bap," she quipped early on in the show to a chorus of cackling from the Grand Opera House's mid-week audience – a very different one to last week's demure gatherings for Swan Lake, and one with elements who just might appreciate reality shows like Geordie Shore and a good Ann Summers' party.
The vast majority at Wednesday's show were women – of all ages – in pairs, or small groups, although I was surprised to see quite a few men accompanying their wives, or girlfriends.
They seemed as amused as the ladies by playwright Leesa Harker's hilarious follow-up to 50 Shades of Red, White & Blue, the equally naughty one-woman show starring the gifted actress Caroline Curran as the gross, but kindly Maggie Muff.
I haven't heard such a reaction from an audience since May McFettridge squawked Adele's Skyfall at the Christmas panto; nor have I ever seen a production with such a succession of non-stop gags.
Catherine Cafolla, the Grand Opera House's duty manager, is expecting to see boisterous hen parties in for this weekend's shows.
"We're fully booked for the back-to-back matinees and evening productions," Catherine said.
"The feedback's been great. People are coming in in great form and leaving in even better form. It's amazing how Caroline can hold her own for the whole show."
Chavvy Maggie has a very racy line of patter; it's hard to imagine a male character getting away with her X-rated descriptions of "doggin' in Crawfordsburn" or "buckin'" her neighbouring friend-with-benefits.
Maggie gets away with it because she has a heart of gold behind the big tough millie exterior and she is touchingly loyal to her hapless friend, Big Sally Ann, who she fears she's going to lose to one of "those eastern Europeans coming over to take our mates".
That line got one of the biggest laughs of the night. Caroline Curran (far right) is great at accents and has good comic timing and she's not afraid to jerk her hips and waggle her tongue for Maggie's saucy accounts of her casual sexual encounters.
It's the role of a lifetime for the drama graduate, who has starred in local productions of Shakespeare's Macbeth and Jane Austen's Pride And Prejudice.
"Maggie has reawakened a dirty, dark humour that the people of Belfast love to laugh at," the actress said. "I'm so happy she came into my life – I thank my lucky stars every day that she did."
Caroline does have a very sharply observed, laugh-a-minute script to work with. Like James Young and Nuala McKeever before her, Leesa Harker has a keen ear for the vernacular and colloquialisms of both east and west Belfast and a punchy urban rhythm in her dialogue.
Her comic creation likes nothing better than a bottle of "Buckie" (Buckfast), which she gets delivered with a packet of "fegs" from "the taxi carry-out" when she's not "skint Eastwood", while her deadpan friend Sinead from the west doesn't like the "peelers" and has a father who's suspicious of "Prawds".
Although it's a one-woman show, Leesa has created through Maggie Muff a cast of vivid characters the audience can easily recognise or relate to, hence the high ticket sales. The wildly popular playwright agrees with Joan Rivers's observation that all good comedy is based on outrageous honesty.
"Oh, I love Joan – I follow her on Twitter," she told me in the interval. "Maggie's outrageous, but at the same time you don't have to be some sort of a ladette to be funny. I'm a feminist – and you can be a feminist and glamourous at the same time. This play is naughty, but it's not sleazy. If you come to see the show to get off on it, there must be something seriously wrong with you."
Comedians Peter Kay and Miranda Hart have also influenced Leesa, a mother-of-two and Open University graduate (in English Language and Literature) from east Belfast.
She started writing poems as a child about her granny's flatulence and there's plenty of toilet humour in Dirty Dancin' In Le Shebeen, including one uproarious tableau involving Big Sally Ann having a bout of diarrhoea on the dancefloor, while wearing skin-tight leggings.
It's a side-splitting piece of writing worthy of the hit film Bridesmaids and its hilarious food-poisoning-aftermath scenes.
Among those wailing with laughter was former PUP leader Dawn Purvis, who has written her own play as part of the Flesh and Blood trilogy coming to the Opera House next month.
"I've no make-up left on my eyes from crying laughing," she said after the first half.
"Leesa has a gift and it's getting people who wouldn't normally like theatre into the Grand Opera House, and that's a very good thing. I'm delighted that she has set up her own theatre company; it's great for her."
It is quite an achievement nowadays to get these numbers of mostly young women dragged away from the telly and Netflix and social media, and into this bastion of the arts. Most had seen or read 50 Shades Of Red, White and Blue and wanted to see what happened next.
Others, such as friends Jackie Jameson, Lylia Elliott, Emma Denby, Jane Davidson and Grainne Boyle were there for a big night out, loading up on nuclear blue alco-pops in the interval. Their joint verdict: "Absolutely brilliant – even better than expected."
Fiona Adair admitted to squirming a little at some junctures – she was there with her teenage son, Joel. "There were a few embarrassing moments, given I'm his mother, but it's very well done and the music adds to it."
Lorna Coleman (51) and Robyn Reney (26) were there for a "good girly night out", while Bill Moody (47) bought the tickets for himself and wife Carla (43) to celebrate their 22nd wedding anniversary.
Also in the bar beforehand was redhead Emma Barry (26), the Dublin version of Maggie Muff. "The response in the south has been great – we had to change some place-names, but they totally get the Belfast humour," she said. "It's been great fun touring."
Touring the Republic has meant some tweaking by Leesa and director Andrea Montgomery, a Canadian who grew up in Thailand, Indonesia and Switzerland. She has worked with Nuala McKeever and directed 40 professional theatre productions all over the world. Her approach to comedy chimes with that of Larry David of Curb Your Enthusiasm: unleashing the normally unspoken.
"In this case, it's Maggie coming out with the very naughty things we'd like to express, but don't," said Andrea. "Maggie comes straight out and says the things we'd never have the nerve to say and gets away with it.
"But it's also a play about friendship, a type of bromance between two women, Maggie and Sally Anne. It is such fun to do – and it has heart."
Dirty Dancin' In Le Shebeen runs at the Grand Opera House until Tuesday, April 22. Tickets – £16.50-£30.50 – from www.goh.co.uk or box office 9024 1919