Mike Bonnano and Andy Bichlbaum
The Yes Men... Mike Bonnano (left) and Andy Bichlbaum. Photo: Dan Chung Dan Chung/Guardian

For months leading up to today's election, George Bush and his campaign team have been criss-crossing the US in a fleet of red, white and blue buses bearing the words "A Safer World - A More Hopeful America", followed close behind by several coachloads of journalists. Amid the mayhem that attends the motorcade, few people seem to have noticed anything odd about the occasional appearance of another, unauthorised bus, bedecked with near-identical patriotic graphics and a huge photograph of the president's grinning face.

The somewhat defensive slogan "I'm telling the truth!" should probably have rung alarm bells. So should the fact that the zealous campaigners on board claimed to represent a pressure group called Yes Bush Can. Mainly, though, alarm bells did not ring - which is why, over recent weeks, numerous loyal Republicans have happily signed a pledge in which, among other things, they agreed to host a permanent nuclear waste storage facility in their neighbourhood, promised not to have sex before marriage, and specified which branch of the military they would prefer their children to join to fight America's forthcoming war against North Korea.

"That's what's amazing about the discourse in this country," says Mike Bonnano, one of the two weapons-grade ironists behind Yes Bush Can. "People are so used to complete absurdity that nothing surprises them any more."

Bonnano and his accomplice, Andy Bichlbaum, are used to people not getting their jokes. Fury and incomprehension were the main reactions to one of Bonnano's most celebrated youthful stunts when, in the 1990s, he and some friends bought crateloads of Barbie Dolls and GI Joe toys, swapped the voiceboxes, and smuggled them back onto the shelves in time for Christmas. Children and parents across America were confronted with testosterone-drenched killing-machine Barbies, and soldiers who just wanted to go shopping.

But for failure to bat an eyelid in the presence of satire, the Oscar must go to the delegates at a textiles convention in Finland, featured midway through Bonnano and Bichlbaum's forthcoming documentary, The Yes Men. The film recounts what happened when the pair set up a fake World Trade Organisation website, then began to receive - and accept - speaking invitations from unsuspecting conference organisers. Jonathan Swift, meet Ali G.

The textiles experts don't blink when Bichlbaum, posing as a WTO economist named Hank Hardy Unruh, delivers a thoughtful lecture on slavery, explaining that the real problem with forced labour is the unfortunate burden of having to house and feed your unpaid workers: paying exploitative wages to workers in the developing world, he notes, is really far more cost-effective.

"We call it identity correction," says Bonnano, sipping coffee with Bichlbaum on a rickety bench outside a cafe in Manhattan's East Village. Bush, and the WTO, "are doing all these things and then presenting them through this weird distorting lens - this bizarre convex lens that makes them reversed, so that the Clean Air Initiative is really about making the air dirtier, and the Healthy Forests Initiative is about cutting down the trees. We're just providing the reverse lens so that it comes out clear again at the other side. But a lot of people aren't ready to accept that clarity yet."

Both men used to teach media theory, and it shows: they have a ready scholarly answer to the question of why people tolerate their absurdity. "Often, I think they just respect the authority of the World Trade Organisation," Bonnano says, citing the 1950s experiments of the psychologist Stanley Milgram, who found that members of the public would deliver what they thought were fatal levels of electric shock to strangers if commanded to do so by a figure of authority. The Milgram experiment "actually involved them doing something. This just involves them listening without reacting negatively. It's a straightforward psychological phenomenon."

If there is something a little disturbing about Bichlbaum and Bonnano's activities - which are now a full-time job, funded by a handful of particularly indulgent charitable foundations - it has to do with the vulnerability of some of their victims. The Yes Bush Can team, for example, recently solicited signatures in favour of tax cuts for the wealthy outside 99-cent stores, whose low-income clientele hardly seem like the ripest targets for mockery. They have an answer for that too, though: they're not just sending people up, they insist, but seeking to politicise them. "We want them to figure out what's happening - that's the best thing!" Bonnano says.

The documentary is at its most satisfying, therefore, when a class of university students are provoked into open rebellion against Bonnano, posing as a representative from McDonald's. He begins his lecture by handing out free Big Macs, then strolls to his overhead projector and begins to outline his firm's latest act of corporate responsibility: converting first-world human waste into fast food for developing countries. The students begin to study their burgers sceptically. Then they start throwing them.

Oddly, neither Bonnano nor Bichlbaum ever burst into laughter mid-performance. "It's weird," says Bichlbaum. "It just doesn't occur to you to crack up." And in any case, the response of an audience when realisation dawns is not necessarily amusing, as the two discovered recently when they attended a conference in Florida on how to protect children from internet pornography. (They were posing, needless to say, as representatives of the Bush campaign, having been contacted through their website CheneyBush.com.)

"It was organised by this strange, cultish group, the International Web Police - they're all about making people afraid about what lurks behind every corner of the internet," Bonnano recalls. "So we worked up this lecture that involved a baby doll and a bucket of water labelled 'Porno', and we demonstrated how a normal baby, without any protection, could simply be dipped in the bucket and submerged in pornography."

But the Bush campaign, the men told the largely conservative crowd, had a plan: the Patriot Act. "The Patriot Act was a plastic bag," Bonnano explains. "So we put the baby in the plastic bag and sucked the air out with a vacuum cleaner, and the baby collapsed into a shrivelled nothing, and we say: 'Look, the Patriot Act is working!'" The audience looked on appreciatively.

"Then at the end, Andy's unpacking the baby, and he shouts: 'Now, if John Kerry gets his way, the baby's going right back in the bucket of pornography !' And he throws the baby from across the room, into the bucket. And somebody at the back finally says, 'What's going on here?' And then it was like all hell broke loose. We ended up being run out of the room. They were screaming at us about the horror of what we had done."

Bonnano shakes his head, presumably at the memory of the conferencegoers' violent response, although quite possibly also at the concept of a lifestyle that involves travelling to Florida in order to throw a doll into a bucket of water in the first place. Such are the duties incumbent upon a liberal satirist in the era of George Bush. "Of course," he adds, "if Kerry wins, we'll immediately turn it all against him."

· The Yes Men is released in the UK in January www.theyesmen.org