You might be tapping your pencil on the table as you read this sentence. One of your children might be imitating the beat of a favourite tune, making guttural cymbal noises with their teeth and tongue. Or that colleague from across the hall might be drumming out a pattern on the photocopier, relieving the boredom of waiting for pages to churn out, writes ChristineMadden

"Rhythm is a universal language," says Luke Cresswell, who with Steve McNicholas founded the performance group Stomp, whose show opens at Cork Opera House tomorrow evening. The group defy classification. Their publicity describes their performance as "a unique combination of percussion, movement and visual comedy", but Cresswell once added: "At the end of the day, Stomp is what it is."

"In this post-Riverdance world," says McNicholas, "we're now described as percussion theatre. But in our first three to four years there was nothing else in that category."

Stomp's origins date back more than 20 years, to when Cresswell and McNicholas were street performers. After getting together in 1981, they put on a series of street musicals at Edinburgh Festival Fringe. "I was a singer and guitarist," says McNicholas, "and Luke was a drummer with a hankering for performance. He wanted a slice of the action, so he freed himself from the drums and found ways of doing percussion and moving about using objects on the street - anything from a bicycle to a policeman's helmet.

"It came from a series of experiments, one-offs. We were doing solo rhythmic performance projects, some of them stupidly arty and some very funny. Typical things would be making suits of armour out of cymbals and walking into the sea and nearly drowning. Or we would suspend ourselves off the pier in Brighton and actually play the pier, hanging off it. It was looking back on a lot of those that we started to think, what if we put a whole thing together? And all of a sudden it seemed like a clear path, as if we'd been heading for this without really knowing it."

But a percussion-theatre show takes more than two, no matter how much energy they have. In 1991 Stomp evolved into eight performers, "and the only form of communication they have," says McNicholas, "is through rhythm", using anything from anvils to zips to create textures of rhythm and cohesive, co-ordinated movement to generate it. And it's not only a conversation, adds Cresswell. "I think it's like one-upmanship: some people showing off, some people being shy, some being cocky, some being clever and some being very funny. You see a big spectrum of communication but using rhythm instead of speech."

To create that beat Stomp use just about anything they can get their hands on. Cresswell rattles them off: "Ice picks, kitchen sinks, bits of cars, fridge doors, ladles, plungers, brooms, apples, rubber gloves." What did they do with the rubber gloves? "We squeaked the sinks with them. Those Marigold gloves, you get a nice reggae squeak. I'm surprised how musical things can sound. Like if you pick up five paint scrapers you'll usually get a different note from each one. If you collect a few of the same things you'll usually find some sort of pitch or scale, and you can arrange them then and get some sort of melody. It's like a big DIY department, plumbers' convention."

Stomp have come a long way from their beginnings knitting street-theatre acts into a full-length programme. As they gained popularity, it became clear that the eight "average people" in the one company weren't enough, so they expanded. They might now have up to five Stomp companies operating around the world at any time.

"It's not like a franchise, though," says McNicholas. "We have creative control over all the companies. If you saw the show in New York and then in the West End you'd see pretty much the same features, but the flavour of the show would be quite different. We've made a conscious decision not to replicate the original cast, to keep everyone's individuality."

To do this Cresswell and McNicholas run workshops, both for hopeful Stompers and for those who just want to have some fun. They've recruited people over the years to take part in the production. "It can be anybody," says Cresswell. "from a trainspotter musician to someone who doesn't know the first thing about music. You can be thin, fat, short, tall, all different nationalities, male, female. We just look for a mix when we try to cast a group."

The programme then works these individual characters into not roles, necessarily, according to McNicholas, but functions. "For example, 'Sarge' has the function to lead the group, to be the main conduit of audience interaction. He would be the person to whom the audience looks to see what's going on. That was Luke's role from the beginning, but how it's expressed is up to the individual performer."

"Ozzie" brings light relief. "He would be a comic character, the butt of the jokes, but he also calms things down a bit, helps things move from tribal rhythmic along the journey of the show. So it's a set formula, but there's a lot of room for the individuality of the performers to shine out."

Advertisers were quick to pick up on Stomp's success. Companies with products to sell recognise the edgy appeal of the Stomp performance. Stomp have done a variety of things, including a chilled commercial with blocks of ice and ice picks for Coca-Cola. The experience will help them with an ad for the US television station ABC on sport activity. "We've done ice before," says McNicholas, "so we'll explore it more specifically. We'd be interested in finding out what kind of rhythms you can make with skaters on ice, see if there are previous Stomp films that would work on ice, make rhythms with that swish-swish" - he replicates the noise expertly - "sound of skates. We know from experience that you can make sounds with ice. You ask yourself, what happens with ice? You put together things that people expect to do with ice and make them musical. Anything from ice cubes in glass to ice picks."

The ads and shorts have been perfect training for their own film project, Pulse: A Stomp Odyssey, an IMAX film that has scooped many awards, including the Prix Raymond Lefèvre at the Cinéma Britannique festival in France on the eve of their run in Cork. "We were amazed actually. We were up against films like Love Actually, Calendar Girls and Dirty Pretty Things. We never expected to get an award. But we didn't get anything to carry it in - it's broken."

Pulse is "a kaleidoscopic trip around the world of rhythm", as McNicholas describes it, with acts such as the Kodo drummers of Japan and Eva Yerbabuena of Spain. "We let everybody do their own thing; we wanted to show people what the carnival rhythm was like in Brazil, elephant processions in India - it all ties together."

They're looking forward to coming back to Ireland: they haven't performed here since the mid-1990s. "We get a warm response from the Irish. They're very musical people, more than the English," says Cresswell. They cite Irish dancing and Riverdance as examples of the Irish affinity for beat and rhythmic dancing.

"Rhythm is used around the world and isn't our creation by any means," Cresswell says when asked to explain Stomp's success. "Everywhere in the world, in every country, there'll be some culture that uses rhythm in some way - a very sexy way, or very violent way, but it will be there in some way. Stomp appeals to that."

Stomp opens at Cork Opera House tomorrow and continues until Sunday