"We've never lost a goldfish doing this show," say Spain's La Carniceria Teatro.

It's a fact, one would imagine, of which most theatre companies could boast.

But then most theatre companies don't produce theatre in which an actor holds a goldfish bowl in outstretched arms, slowly draining it of water until the creature lies helplessly flapping at the bottom.

With a name translating as The Butchery Of Theatre, La Carniceria Teatro specialise in such darkly visceral, tightly focussed and horribly compelling moments.

And, judging by their last piece (I Bought A Spade At Ikea To Dig My Own Grave was accompanied by live Puccini arias, featured performers with credit cards wedged bloodily in their foreheads, and challenged critics to review the smell of cold lasagna), the UK premiere of their latest work will prove the most controversial ticket of the Festival.

Like its predecessor, The Story Of Ronald, The Clown From McDonald's is an attack on consumer mentality conducted via a series of striking tableaux.

In an orgy of over-consumption, the semi-naked performers writhe in a flood of supermarket produce - wine and milk for the aperitif, hamburgers, ketchup and Coke for the mains - while a scandalously funny script (relayed here through surtitles) keeps them in continual dialogue with the audience.

It sounds like theatre as extreme aversion therapy, and if that's the intention, it certainly worked on Festival director Jane McMarrow, who, when she first saw the show in Avignon last year, "came out feeling like I'd been beaten around the head".

"I can honestly and truthfully say I've never seen anything quite like it," she says. "As a Spanish company, they have such a different approach to putting work on - it's incredibly passionate, very in your face and quite shocking in places.

It's an assault in many ways. But I hope, Brighton being politically what it is, that people will take a risk and get an awful lot from it."

Before he left the industry in disgust, director and playwright Rodrigo Garcia was once an advertising creative charged with flogging the produce he now spreads across stages.

And, hammering home a message of anti-capitalism and anti-globalisation, La Carniceria Teatro is essentially the means by which he has, since 1989, been enacting his revenge.

Yet Garcia admits that what he learnt in advertising - the iconography of the image, how to make the biggest impact in the shortest possible time - have become the tools of his new trade.

You are guaranteed a gripping night. But you'll need a stronger stomach than the maker of Super Size Me.

Not for the faint-hearted, The Story Of Ronald, The Clown From McDonald's is set to rip the guts out of conventional theatre and have them for breakfast.

Starts at 8pm. Tickets cost £18/£12.50, call 01273 709709.