Four years ago, Shane Langan (24), who was studying film in college, decided to get together with his old friend Niall Gaffney (24) and stage auditions in the Dawson Lounge in Dublin for a sketch comedy show. Amy Stephenson (23) and Philippa Dunne (25) came on board.

Originally they wanted to film a pilot for TV.

"It wasn't very good, " Shane confesses. A year later, stand up comic Rory Connolly (25) joined the fray.

They started gigging in the Ha'Penny Bridge Inn in Temple Bar. Tuesday night's Battle of the Axe competition became their forum.

"We did a sketch one night and we won it, " says Niall. "We were king of encouraged by that. We'd already booked ourselves into Edinburgh (Fringe Festival), so we thought 'uh oh, we better get some practice in.'" The group are probably best known for their film series 'Dublin Stories' which has spread on YouTube through a network of Irish blogs, culminating in thousands of views for each episode.

The humour is deadpan, left-field stuff.

One is an account of a man obsessed with ATM machines in an overly-eager trainspotting manner. Another focuses on 'Frank', a macho Dublin layabout who spends his time "hanging around the gaff" with a can of Budweiser and his Liverpool jersey to distract him.

The screwball, slow-building, character-driven humour has endeared them to many people, and their performances at the Edinburgh Fringe Festival last year will be built on when they return next week, this time performing their entire show in a swimming pool.

"It was a 60-seat venue, " says Amy about last year, "and we probably got on average 20 each night, and on the last night about 45 or so. There was some GAA match so there were loads of drunk Irish people."

"The average in Edinburgh, I've heard different ones, " Rory continues, "I'd say around seven, but it's probably around 10. So for us to do what we did without being in the programme. . ." This time Niall finishes his sentence, "We had already gone over there, underdogged, " he says, inventing a new word.

Their brand of comedy is intriguing. At first, you think the punchline is in the expert creation of a character's subtle faults and contradictions, but then another completely obscure joke is thrown into the mix. (Like the brother and sister combo. She's protective and concerned about him, as any sister is. Then it becomes apparent that he can only say one word. It's bizarre, brilliantly wry stuff. ) Their director Clare McQuaid joined the team about a year ago after directing a play at a theatre festival. "We hadn't got a clue what we were doing, " Amy says, "none of us had done any theatre. . . she made our show make sense. It was brilliant to have someone with a theatre background."

And so, to a swimming pool.

They had spotted the venue last year in Edinburgh, but it was showing a sold-out Greek tragedy.

This time, they were determined to get it.

Now, there are logistical problems.

"You don't happen to have a body board, do you?" Niall asks out of the blue. They need waterproof props. Niall rang the foam shop on Capel Street. "There's a foam shop on Capel Street?"

someone asks, and then they all agree on the brilliant randomness of Capel Street.

Comedy in Ireland is big business. Exporting our comics provided the country with a great entertainment boom in the '90s and now, as Niall puts it, "every pub that has an upstairs is a comedy club."

But Diet of Worms are unique in their youth and collective collaboration. They think about whether there's another nonimprov sketch group, worried whether they should say they're the only one in Ireland just in case there's another one hiding out there.

A fundraising gig at the Village on Wexford Street was a great success. Their worst so far was when they wandered out of Dublin to perform in Cork. Amy begins: "we were doing a gig in CIT, and we were so excited about it. We flew down on our 10 Ryanair flights and everything, and we had a friend who had brought his camera that day and he was going to document it. Then we arrived in this hall with an eight-second delay of an echo."

"There was an ATM beside the stage that people were using, " says Rory, "and video games and stuff and a gunge tank as well."

Niall continues, "competing for sound with a gunging and a video game competition where they were looking at us going 'f**k's sake' and turning up the sound."

Shane looks pensive, "at the start there was a really good crowd.

And then people just started leaving." Amy is the optimistic one, "I kind of felt like I enjoyed it in a way because it was so awful.

Nobody could understand, or get, or hear what we were saying."

Philippa agrees, "that gig was great for us, because we thought if we could survive that, we could survive anything."

"We got our first and last 'get off the stage' shout, " Rory concludes proudly. As they bounce off each other, the kernels of gags that become sketches are almost visibly jumping around the conversation. Niall does a rather accurate impression of a coffee machine in Shane's direction after talking about an episode of Garfield where the cat goes into the future and lasagne is served in pill form. And it's all a dream. "Then he goes to the dad, yer man John. . ."

The group debates that 'John' in Garfield could not have been the cat's father. Like most people their age, the conversation slips into '90s nostalgia. The ladies in the group talk about how women in cartoons always play a central role in saving the day . . . namely Penny in Inspector Gadget. Clare confesses that when she was a child, she used to draw boxes in her books and hide in the wardrobe and pretend to be her.

"I shouldn't have said that." She hangs her head, laughing. Amy tries to remember the names of the characters from Captain Planet. The Transformers film is discussed at length. Despite awful reviews, Rory thinks it's amazing.

Niall is scared of the new Simpsons film. They talk about 'Spider Pig' in the Simpsons film trailer.

And as the conversation is just about to end, they all decide that yes, they'll have one more drink.

Six Heinekens and a Corona please. . . "what was the deal with the baby in Ghostbusters anyway?" asks Niall.

And they're off again.