"The word `hybrid' is good," he says. "This is something that crosses over from being an art exhibition to being an art fair, a country fair, a school fete, Brick Lane market, a car-boot sale, a fancy-dress party and a holiday."
Any more detail than this is hard to come by. Turk may be organising The Articultural Show, the fifth fair of its kind that throws artists, performers and the public together into one big, interactive melting- pot, but he's the first to admit that he's short on facts. "I won't really know until the day what's going to happen. I think that's part of what makes it so special and fun. If you try to really predict and hone these things too much, they do lose a certain spontaneity."
Given his own work's fixation with the myth of the artist and the sometimes ludicrous extent to which art is valued by its signature alone - his own signature having become his trademark - Turk is fully aware of the fair's great levelling potential. Here, young graduates will set up stalls alongside established Britpack artists, and in this context who's to say one is better than the other? You can get an idea of the off-the-wall nature of the event from Turk's past contributions. His 1994 performance was accompanied by David Bowie's "Scary Monsters". "I was trying to do a Leigh Bowrie impersonation. I re-recorded the track with an extra bit over the top of it with me singing "scary monsters", and then I had this weird costume made out of the foil that you put on after a marathon. I had a fake bottom and a mask and a stocking over my face, a Bavarian hat and a wig. And basically I did a mime to it. It was some sort of bizarre karaoke, Carry On kind of thing, and people just stopped and said `What?'"
There are rumours that this year he'll be running round signing bodies, in the style of his hero Manzoni, but he's being evasive; he may, he may not. Some things, however, he can confirm. There will be a Brian Sewell stall where people can go along to be made up to look like Brian Sewell. (The real-life Brian Sewell has also been invited for a makeover into himself, although Turk doesn't know yet whether he's taken up the offer.)
The artist Angus Fairhurst will be inside a gorilla costume, and if you can catch him you can play pin the beard on the gorilla. The comedian Arthur Smith will be selling poems. There'll be a champagne and sperm bank stall ("I don't know what that is," says Turk), a molten lava happening (I'm not sure what they're doing"), a jam and cake stall, a dippy luck where players have to fish for their prizes with a fishing-rod, a kids' area, an absinthe bar and, of course, there'll be art for sale. If you want to go shopping, you'll need to change your sterling into sheep - the currency for the day.
Turk seems a little snowed under. The fair is being organised from his Filofax-cum-filing-cabinet thrown on a table in the corner of his studio. The phone rings constantly as last-minute ideas get under way. Disconcertingly, a wax head lies under wraps nearby, the beginnings of his "Last Bum", a life-size sculpture of a tramp, modelled on himself. It all seems pretty ramshackle, but then an artistic event run by artists couldn't be anything else, surely? This is as close to an artistic happening as we're likely to get these days - nobody wants to be pinned down. Everyone is keeping things vague, so that come the big day they will be free to be creative in any way they please.
The first three fairs, A Fete Worse than Death (1993 and 1994), and the Hanging Picnic (1995, when Matt Collishaw and Gary Hume hung their works on the park railings in Hoxton Square) were organised by the art entrepreneur Joshua Compston in 1993, but after Compston's death from drinking ether, Turk took over where his friend left off with the 1997 Live Stock Market.
"I think it's a very important space for artists to have," says Turk. "I not sure I'm the best person to do this; it's not my best skill; but it does allow me to celebrate, think through, or to be in the shoes of my friend. It helps to keep up his profile and it makes some sense of what he was trying to achieve." Compston wanted to break down barriers and "bridge the gap between art, advertising and manufacturing".
Turk's sense of fun - which saw him dressing up as a tramp for the opening of Sensation - seems perfectly suited to organising such a haphazard, creative free-for-all. At the Live Stock Market he wandered around in a T-shirt with "Morris" on the front, and when asked where the Morris dancers were, gave a quick little dance of his own. His enthusiasm is palpable, although he's disappointed that some of his more ambitious ideas had to be shelved. Plans for a fly-by to drop hundreds of little doughnut- carrying parachutes over the fete were scrapped for legal reasons, although Turk was taken with the idea of these "bouncy, squishy, bomb things" floating down from the sky. And the dancing diggers - a company of Somerset farmers who do a synchronised driving routine with their machines - is also looking doubtful.
There will, however, be a cheery re-enactment of the Jones Town mass suicide. "A friend of mine is trying to organise a re-enactment of Jones Town - where lots of people drank poisoned tea and committed suicide en masse - so he's doing a version of those staged medieval battles." The event is advertised on the Internet and it's looking hopeful that the full quota will be reached.
As for which Britpack artists will be there, Turk is reluctant to be drawn; that whole celebrity thing is what they are all trying to get away from, at least for a day. With a little coaxing, however, he reveals that Gillian Wearing, Tracey Emin and Adam Dant will be doing something, and possibly Chris Ofili. There may be others, but they may be in disguise, he says mysteriously. It won't matter if you're Damien Hirst, an art student, or a member of the public wandering by on the day, as Jessica Voorsanger's Fanogram 2 delivers celebrity status to one and all. "She's done a fanogram before and it was brilliant," raves Turk, "It's a group of six 12-to-15- year-old girls and you can hire them to do a hit. You point out who it is and they scream after this person in the street `Ah, aah', creating mayhem and getting their autograph books filled. It's really quite scary when they're let loose."
The Articultural Show, Royal Festival Hall, River Terrace and Queens Walk, London SE1 (0171-921 0600), Saturday 7 August, 2pm-8pm