by Mark McGregor
BBC News Online, Leeds
A shop in Leeds is set to become the latest venue for the flash mobbing craze currently sweeping across the globe.
Matthew the organiser already has his shop target in mind
Since the first reported "hit" at a department store in New York in June, net-savvy strangers in cities across the world have been meeting up to take part in the phenomenon.
Shop owners suddenly find themselves overrun by hundreds of customers, only for the crowd to disappear after a mass - and always bizarre - act.
In New York they broke into spontaneous applause, in London they stared at a sofa and in Boston crowds swamped a card shop.
But so far only one man knows what will happen in Leeds on Saturday - and when BBC News Online tracked down the city's first self-styled flash mob boss he was staying relatively tight-lipped.
Matthew, a 16-year-old A-Level student from Whitkirk, would only tell us that his event would be different to all those that had gone before.
In London, they gathered at a sofa store
He said: "We have our plan for what everyone's going to do but it's top secret.
"That's part of the fun of it - we're going to do something different, something abstract.
"It's going to be something you wouldn't expect to see if you walked into that shop."
Flash mobsters are mobilised by mobile phone and the internet, handed details of the meet point and are told to disperse until the chosen moment.
Matthew describes it as a "practical joke", although some people view the gatherings as a subversive act.
Flash Mob Leeds rules...
No smoking, eating or drinking in the shop
No stealing or vandalism in the shop
Follow all the instructions exactly
Do not go near the shop until the given time
Throw away these instructions after you have read them
Some participants in America say it is like the movie Fight Club without the violence.
But Matthew says the British version is tamer in its ideology.
"The point is there is no point. It's just easy to do, everyone can join in and its something different."
Unlike Fight Club, the first rule of flash mobbing is tell as many people as possible and Matthew is expecting individuals from across West Yorkshire to take part on Saturday.
His website has been up less than a week but already boasts 60 members, most of whom are planning to bring friends for the inaugural hit.
He added: "There are families, businessmen and all kinds of people down to your teens and students - one guy is bringing his mum."
One of the would-be participants, Jim Hudson, a 35-year-old IT manager from Bradford, told BBC News Online he had been looking for an opportunity to get involved in a flash mobbing since hearing about it on Radio 4's Today programme.
Boston mobsters swamped a card shop
He said: "I heard it, instantly started laughing and thought: 'I'd love to take part in something like that'."
After finding out about the "Leeds cell" on the internet Mr Hudson has been counting down the days to the first event and cannot wait to take part.
He added: "I suppose I'm doing it because I'm going through a second childhood - it appeals to my sense of humour.
"I'm just going to turn up and keep an open mind. Whatever it is we end up doing it will be an absolute scream that's for sure."
Sofas on alert
Britain's first taste of flash mobbing came at central London store Sofas UK on Thursday 7 August and Matthew has no plans to target a similar shop because "the sofa thing has been done".
Nevertheless, when the phenomenon was explained to the manager of Sofa Workshop in Leeds city centre, Sarah Sutton, it still made her a little nervous.
She said: "We're three women who work here so it could be quite intimidating I guess - especially if one of us was one our own.
"It could be very annoying if its was a Saturday and we lost a lot of sales through it.
"But as long as they didn't cause any trouble and wreck the joint and weren't here for a really, really long time I think I'd find it quite amusing."
With events springing up in cities all over the country and the media coverage already reaching saturation point in the US, Matthew is giving flash mobbing "about four weeks before it dies off".
Matthew says he just wants the mobsters to enjoy themselves
But he is determined for people to enjoy the concept while it retains its popularity.
He added: "I've never taken part in one so it will be an experience for me as well.
"We want the shopkeepers to have a laugh and enjoy it too - we certainly don't want any harm to be done.
"I would find it quite amusing if I did get in trouble... but I'd have thought police should be out catching criminals not someone playing a prank."