Watch out: there's a viral advertiser about

A new strain of word-of-mouth disease is sweeping the nation. And you might not see it coming...

A few years ago, the height of advertising brilliance was Nick Kamen's laundrette striptease. Now, however, advertising agencies have adopted tougher, sneakier and subtler tactics to grab our attention and our cash. Their techniques range from the devious to the downright rude, and their allies are 10-year-old boys called "alpha pups", trendy club DJs, cool shop assistants and even pub toilets.

"People are getting smart about when brands are trying to persuade them to do things they don't want to do," said Will Collin, from the ad agency Naked Communications. "Now, if you want to promote a new brand, you have to be extra smart. It's like a chess game, and we've got to grand master level now."

Naked has been at the forefront of one tactic increasingly being used to sell products to specific audiences by drawing them into a shared joke: brash, in-your-face, stunts.

In May, they launched the vindaloo variety of Supernoodles, aimed solely at twentysomething lads, by wreathing pub toilets with police-style warning tapes, flashing lights and even fake tapes of people screaming as they sat in the cubicle.

It was crude, cheap and effective. The vindaloo variety is now a permanent part of the Supernoodles range, and cost just £200,000 to market. "Young men in particular are very bullshit-sensitive, but they're happy to go along with you if you talk their language," Mr Collin said.

Such techniques are now regularly used by firms such as Selfridges, Nike and Channel 4. However, most new brands hoping to become cool use variations on the latest buzz word in marketing: "viral advertising". It uses word of mouth and deliberate placement of products on style-setters such as DJs and models without any advertising. It has been used by the world's largest firms: the watch-makers Casio and Citizen, Coca-Cola, Levi's and Nike.

Success can vary. While Levi's "engineered" twist jeans have taken off after being placed with "style leaders", Casio's G-Shock watch for clubbers flopped when club DJs refused to participate. Launched 18 months ago, it is now off the market.

Coca-Cola chose ultra-cool parties hosted by the style magazine Dazed & Confused, the lingerie company Agent Provocateur and the club Attica to promote its energy drink Burn. Coca-Cola deliberately distanced itself and refused to advertise it, but it now sells in 350 clubs and bars.

The ultimate viral advertising techniques have been pioneered in the United States. One involves using undercover sales staff, described coyly as "ambassadors", to pose as ordinary people who ask loudly for the latest drink in trendy bars.

The major toy firm Hasbro has used "alpha pups", 8- to 13-year-old boys selected from Chicago playgrounds for their ultimate coolness, to launch a new multi-player game called Pox. Hasbro is launching Pox in Britain next year, and is considering using the same technique.

But Alex Batchelor, managing director of the branding consultancy Interbrand, dismisses predictions that this new advertising will replace the traditional 30-second TV ads as misguided. Advertisers have to be careful about becoming too clever by trying to hide products. Eventually, they risk a consumer backlash.

"It flatters us to think that we're becoming more sophisticated," he said. "But companies have to be careful about not being honest. People expect honesty."