Lionel Richie, it's you they're booking for

"That's a nice stereo," says Spencer-Hyde, "but it doesn't have a penis."

"I beg your pardon," says Richie.

"I said it doesn't have a penis," says Spencer-Hyde. "I want a stereo with a penis. And not one of those tiny little Japanese ones either - a good big one."

"Oh," says Richie, clearly uncomfortable. "Well, er, perhaps you could strap a dildo on to it?"

"WHAT?" booms Spencer-Hyde. "Manager! I demand to speak to the manager!"

"Good afternoon sir," says Chris Head, the third member of Richie's troupe, "and what seems to be the problem?"

It would be a shame to give away the ending of this micro-drama, but suffice to say that, from here on in, things go downhill very rapidly for the sales assistant. Anyway, if you really want to know what happens next all you have to do is call 07807 164987 between 11am and 2pm and Richie and his team will meet you anywhere you like in Edinburgh city centre and perform the whole sketch for you. For free. Go on - try it. Just pick up the phone, dial that number and ask to speak to Lionel Richie.

If you've just done that you will have realised (if you hadn't already) that the Lionel Richie I've been talking about isn't the singer of Dancing on the Ceiling fame. No, this Lionel Richie is a comedian formerly known as Barry Ferns, who last month changed his name to Lionel Richie by deed poll so that he could register a Fringe show called This Sketch Show Belongs to Lionel Richie without getting sued. (The show is on at the Underbelly every day at 3.30pm and there are also several spin-off operations - including the dial-a-sketch gig - but more on these later.)

If this sounds like the daftest publicity stunt you've ever heard of, consider that it's already scored Richie a big fat feature in The Scotsman in the middle of August, and that you've now read about a third of it. Daft or not, it seems to be working. And, anyway, the decision to name the show after the R&B legend does have a sort of logic to it, as Richie explains.

"It all started when we heard that Lionel Richie was going around saying: 'Hi, I'm Lionel Richie, can I buy that?' and then sticking a sticker on whatever it was he wanted to buy. We found that really funny so we started making stickers that said, 'This belongs to Lionel Richie', and sticking them to things. We did that for about a year and then we had the idea that it would be funny if there was a sketch show at the Fringe that Lionel Richie owns."

"Then a few things popped up in terms of legal reasons. We thought if we're putting on a sketch show and we're advertising it and saying it belongs to Lionel Richie, then maybe Lionel Richie could get lawyers involved and bankrupt us. So the idea was that if I changed my name then legally I'd be able to say I was speaking about myself."

The team behind This Sketch Show Belongs to Lionel Richie first collaborated in 2004, when they brought a show called OAP Comedy Spectacular to the Fringe, and they have been doing sketch comedy together ever since. When they're not busy with that, Head runs comedy workshops, Richie performs stand-up and Spencer-Hyde has just landed himself a role in Red Shift Theatre Company's Much Ado About Nothing.

Until the end of August, though, these three are going to have their work cut out - not only performing their Fringe show every day, but also working on various Lionel Richie-related side-projects. For starters, they are running a "This belongs to Lionel Richie" photo competition. Whoever submits the funniest picture of an object with "This belongs to Lionel Richie" sticker on it will receive a private view of the show on 26 August, staged in a location of their choice while they receive a free massage and sip free Champagne. Also, at midday on 25 August, they plan to perform their entire 55-minute sketch show on top of Arthur's Seat. "We're probably going to use megaphones," says Richie. "There's only so far the human voice can carry on its own." By far their most time-consuming Lionel Richie-related activity, however, is their dial-a-sketch operation. Between 11am and 2pm every day, they usually receive between five and ten call-outs, most of which they travel to on foot. "It's funny," says Richie, "but nobody seems to believe it's free - everyone treats it with a slight air of suspicion, so when you just turn up and go 'there you go' they're really very grateful."

After their Grassmarket engagement, Richie, Head and Spencer-Hyde make their way to the City Caf, next-door to the Festival Theatre. "These guys are having a group breakfast, so they'll probably be falling asleep after too much bacon and eggs," says Richie. But he couldn't be more wrong. At the back of the caf, the team locate their clients - a group of eight rowdy American students - and, after a brief discussion, they decide to perform the "human beatbox" sketch. This only takes about two-and-a-half minutes, but the Americans lap it up, whoopin' and hollerin' as Spencer-Hyde launches into a couple of deliberately abysmal beatbox routines.

Even though a slightly sour-faced waitress pushes past the actors just as they're about to deliver the punchline, they still receive hearty applause at the end. "That's possibly the most enthusiastic crowd we've ever had," says Spencer-Hyde.

Surprisingly, perhaps, This Sketch Show Belongs to Lionel Richie has yet to be ejected from a pub or restaurant. "It's not something most people have seen before so they don't know how to deal with it," says Head. "It takes a while for them to go, 'Right, this shouldn't be happening, I don't want it to happen.' Plus, when you're in a performance zone like that you're quite hard to approach - it's difficult for people to go up and go, 'No, stop this, get out.'"

At the end of every mini-performance, the actors are sure to plug their full-length show, dishing out free pens, badges and, of course, "This belongs to Lionel Richie" stickers. But is this hugely labour-intensive advertising exercise any more effective at pulling in the punters than, say, simply flyering on the Royal Mile? Our next stop is the Southern Cross Caf on Cockburn Street. After watching the guys perform the human beatbox sketch to another young couple, Euan and Rachel, I ask them if they'd be more likely to go and see the show having had a dial-a-sketch performed for them at their table than if they'd simply been handed a flyer.

"Absolutely, yes," says Euan, "you have much more idea of what you're getting yourself into."

"And they just seemed like such friendly people," adds Rachel.

Richie, Head and Spencer-Hyde have had a couple of invitations to perform dial-a-sketch routines in people's homes, but more often than not they end up being summoned to cafs, bars and restaurants. They say they'll do sketches anywhere they can, though, and are hoping to receive some more creative requests as the Festival wears on. "I'd like to do one in the Scottish Parliament or in a Portaloo or on top of a bus," says Richie. "I'd like someone to phone us from the number 33 saying, 'I'm just on the top of Leith Street,' and then get on the bus and do a couple of sketches there."

"Someone might even want some distraction while they're at the dentist," adds Head.

You can't help thinking, though, that an invitation from the real Lionel Richie would be the ultimate call-out. The singer wasn't available for comment at time of going to press, but Mr Richie, in case you're reading this, here's that number again: 07807 164987.

• This Sketch Show Belongs to Lionel Richie, Underbelly, until 26 August. For more info on the "This belongs to Lionel Richie" photo competition, visit www.thisbelongstolionelrichie.co.uk