Prankster cinema - that combination of documentary, performance art, slapstick and satire - is scarcely out of its infancy, yet it commands our attention right now like no other genre. Why? Three little words: Sacha Baron Cohen. But while the staging of provocative stunts in public settings might be a new game in cinema, it's worth reflecting on how the rules have changed during the two decades in which it has broken free of its televisual origins. Beginning with Michael Moore's mouldbreaking 1987 documentary Roger & Me, in which the everyman campaigner took General Motors publicly to task for blighting his Michigan hometown with mass redundancies, the genre has become the default option for anyone with an axe to grind or a campaign to wage. Strange, though, that the face of prankster cinema has changed from a schlub in a baseball cap to a preening gay Austrian in pinstripe hotpants.

The roots of prank-based entertainment lie in television, with Candid Camera, which has been spying on unremarkable Americans in bizarre situations on and off since 1948. The show's creator, Allen Funt, shifted the format to film in the risqué 1970 movie What Do You Say to a Naked Lady?, full of members of the public encountering actors in advanced states of undress. Neither hilarity nor commercial success ensued. But if cinema wasn't yet ready to embrace pranksterdom, TV survived on the concept for years. Among the descendants of the Candid Camera format you will find the medium at its satirical height (Brass Eye), and at its lowest ebb (Game for a Laugh, Beadle's About). Sometimes it could get even worse than that, typically whenever Dom Joly and his oversized cellphone were involved.

The hedonistic MTV series Jackass, which spawned two movie spin-offs, grew out of the late-1990s skate-punk culture at the US magazine Big Brother. That publication's then-editor Jeff Tremaine commissioned Johnny Knoxville - his Dietrich, his De Niro, and a man unafraid to insert explosives into any available bodily orifice - to video himself road-testing, on his own body, various self-defence products, including pepper spray and a Taser gun. "The camerawork was really amateurish," Tremaine said in 2005, "but Johnny was just so compelling on camera that I called Spike Jonze and said, 'I'm gonna make a TV show out of this.'" Unlike Moore and his ilk, including Morgan Spurlock (Super Size Me) and the anti-capitalist duo The Yes Men, the Jackass crew had no ambition to change the world, or even to engage with it. "We're just fuckin' around and havin' fun," observed Tremaine. "It always ends up being a little bit funnier if you're naked doing it."

Not all prankster TV was so divorced from reality. With the deification of celebrity accelerating throughout the 1990s, the prankster genre produced its own ripostes and reproaches. Recent years have seen the arrival of Punk'd, a cosy inside-job in which a Hollywood starlet or tween idol might be accused of theft and reduced to tears on Rodeo Drive. But that was nothing more than Noel Edmonds' "Gotcha" practical jokes with Zac Efron or Katie Holmes taking the place of John Barnes and Dave Lee Travis. More ferocious altogether was the work of copper-topped, scrunch-faced celebrity interviewer Dennis Pennis, played by Paul Kaye. Pennis's verbal hit-and-run attacks on the red carpet rarely lasted longer than 10 seconds before a toxic glare or a heartfelt expletive ended the encounter. He asked Steve Martin why he wasn't funny any more, accused Hugh Grant of wooden acting, and memorably enquired of Demi Moore: "If it wasn't gratuitously done, would you consider keeping your clothes on in a movie?"

"I was always quite a shy boy," says Kaye now, "but when I got drunk, I'd do absolutely anything for a reaction. I was full of fear the entire time I was doing Dennis Pennis, so consequently was always full of booze. But Dennis felt like an important antidote to the way culture was going. It did feel genuinely subversive, and I got treated a bit like Robin Hood when I walked the streets of London in the summer of 1996." Kaye's writing partner was Anthony Hines, who moved on to work with Sacha Baron Cohen on Da Ali G Show - and later on Borat and Brüno - once Pennis was laid to rest. "Thinking back to when me and Ant lived in the Chateau Marmont in LA for six months, I was completely out of control," Kaye recalls. "I'd wake up every morning in the most shocking state without any recollection of the night before, and then slowly the memories would come back: 'Oh, shit! I fucked off Charlton Heston! Ben-Hur hates me!'"

While television embraced the cheap, attention-grabbing prankster format with impressive fervour, cinema was slow to see the potential of unleashing preplanned pranks in public. Even Roger & Me resorts to precious little tomfoolery compared to Baron Cohen's films, or The Yes Men. But as documentary was becoming more amorphous in the 1980s through films such as Errol Morris's The Thin Blue Line and Ross McElwee's Sherman's March, Moore spied a niche and claimed it as his own. There was a comic fizz in his spontaneous exchanges with obstinate security guards and anyone else bent on thwarting his efforts to confront Roger Smith, CEO of General Motors. Roger & Me was a hit, and overnight a style of filming associated with frivolous TV acquired some political heft.

Jeremy Chilnick co-wrote and co-produced Where in the World is Osama bin Laden? with its star, Morgan Spurlock, and cites Moore as a key influence. "He's done more for documentary in the US than any other person," he says. Like Moore, Spurlock and Chilnick rely on the frisson that comes from going where they're not welcome, with a camera in tow. One scene in Where in the World ... typifies the hazards inherent in prankster cinema, as Spurlock is hounded in Jerusalem by an increasingly hostile group of Orthodox Jews. "You always want to protect your safety in a situation like that," explains Chilnick, "but you also want that element of danger in the film. If you leave the minute there's something uncomfortable, the audience will sense that - they'll sense that you should've pushed it that little bit farther. Morgan will stay as long as he possibly can, maybe too long in some cases. That's how he gets those kinds of moments that would never arise in fiction."

Indeed, an unsettling feeling that emerges when watching prankster cinema is that the screen is most alive when serious physical injury is in the offing. Several times in Brüno, for instance, you suspect that Baron Cohen is in line for a nice shiner at the very least; the only question is whether it will come courtesy of a redneck hunter, an enraged swinger or an entire arena of disgruntled wrestling enthusiasts.

Chilnick feels that Baron Cohen's work shares some crucial DNA with Spurlock and Moore. "There's clearly more set-up involved on something like Borat than on our stuff, and the premise is evidently comedy first. But in common with Morgan's films, you're seeing a side of America you don't traditionally get to see through regular investigative journalism."

Mike Bonanno, one half of The Yes Men, also feels some kinship with Baron Cohen. "We're doing similar things," he notes, "though his messages are a lot subtler and less overtly political. He's a comedian with political undertones; we're activists with comedic overtones. I know a lot of people wonder why he doesn't engage more. That's why the best stuff is Ali G, where he was so successful at hitting powerful people. It's a little bit pathetic when the target is a bunch of privileged college kids in an RV."

Interestingly, The Yes Men use many of the same devices as Baron Cohen to establish the fake credentials necessary to gain top-level access, including setting up fake websites. Bonanno and his fellow Yes Man Andy Bichlbaum embarrass and shame irresponsible multinationals by delivering off-message speeches on their behalf. Their new film, The Yes Men Fix the World, features footage of Bichlbaum appearing on BBC News 24 posing as a spokesperson for Dow, the company that failed to provide compensation for the Bhopal tragedy in 1984 when 18,000 people were killed, and countless more injured, after a pesticide factory exploded. Live on TV, Bichlbaum offers an unconditional apology for Bhopal, and pledges billions of dollars in compensation. In the few hours before the story was discredited, $2bn dropped off Dow's share prices.

Paul Kaye expresses some ambivalence about the offscreen methods employed in prankster cinema. "I'm going to sound like a real square here but I don't really get off on the whole scamming business, and getting people to film stuff under false pretences. It's not the end product which irritates me so much, more the tossers behind the scenes imagining themselves to be subversive when in reality they're just ringing people up and lying to them."

But what redeems the duplicity of The Yes Men is their air of idealism. Bonnano prefers to describe his work as being based around "actions" rather than pranks, but, whatever you call them, they are bereft of the cynicism and trickery that characterises some prankster films. "It's always rewarding to announce the future you want to see," Bonanno says, "when you have the opportunity to pretend just for a few moments that you're the most powerful person in the room. You can see on people's faces the realisation that this could actually be happening. So you think: why can't we do these things? We have quite a bit of faith in human beings. We don't have nearly as dark a worldview as some free-market enthusiast."

For all that the Yes Men are motivated by genuine social and environmental concern, there are signs already that they are becoming victims of their own success. The day before I meet Bonanno, he and Bichlbaum had attempted to deliver polluted Bhopal water to Dow's UK headquarters, only to find that the staff had shut up shop and scarpered. "They got wind we were coming," he shrugs. "So while it was a victory for us in one way, it was also an example of a kind of assimilation: 'Oh they're coming here, we won't even deal with it.'"

Kaye also experienced a self-defeating change in the attitude of his quarry. "PRs started bringing young starlets over to me at premieres and begging me to insult them," he explains. "We were offered all sorts of stuff and didn't do any of it. Channel 4 proposed a Dennis Pennis chat show, but the thought of taking the piss out of celebrities who were being paid £3,000 to sit there and take it was out the question. That was the antithesis of what Pennis was about. A film was definitely talked about. But I was never really into deceiving people, I knew that much. I liked the simplicity of Pennis, its directness, even if that did condemn him to a short shelf-life. I was so bloody conspicuous and that was really important, I think, because it reinforced the fact that I didn't give a fuck. The motto Ant and I had was: 'Get into a privileged position and then waste it.'"

The key to Baron Cohen's success may lie in his ability to unite the different facets of this youthful genre, making his movies a kind of compendium of prankster conventions. There's the gleeful punk ethos of Dennis Pennis, the satirical impulses of Michael Moore and the meticulously-staged happenings of The Yes Men, all finished off with a glaze of Jackass-style gross-out spectacle. These elements converge in a way that transforms Borat and Brüno into cinematic Rorschach blots in which audiences can discern their own political ideals, or lack thereof.

• The Yes Men Fix the World is released 7 August.