Citizen Kane, Brokeback Mountain--those are movies with artistic intentions. Their titles allude to a complicated protagonist or an evocative setting and promise more intricacies when the lights go down. Snakes on a Plane is a different kind of movie. It's about snakes. On a plane. The snakes bite people. The end. "I knew I was going to do the movie when I saw the title," says Samuel L. Jackson, who plays an FBI agent escorting a mob witness on a doomed flight to Los Angeles. "I think I have an audience member's sensibility, and the title just puts it all right out there. You either get it, or you don't." At various points, executives at New Line Cinema admit they did not get it. "They wanted to call it Pacific Air 121," says Jackson. "I told them that was the stupidest damn thing I ever heard."

So did lots of other people. Because the Internet allows moviegoers to learn about movies before they're in production, a vocal group of connoisseurs--nerds, if you will--were able to keep tabs on Snakes on a Plane. Most saw the title and had the same reaction as Jackson. This, they thought, is the kind of exuberant, self-aware tastelessness that can unite everyone at the summer box office. Not only did they demand that the title stay, they wanted violence, profane monologues from Jackson--the Olivier of the F bomb--and graphic snakebites. And they made sure the filmmakers knew it--not through any organized e-mail campaign but with bizarre spasms of Snakes-inspired creativity. "We were fortunate," says director David Ellis. "We had the ability to listen to the audience before we finished, so we could totally deliver exactly what they dream of seeing."

Plenty of movies get tweaked after test screenings, but Snakes on a Plane, out Aug. 18, may be the first to be changed by audience response before the audience saw it. "Personally, I think it's great," says Jackson. "They saved the movie." When the actor first signed on, he and Ellis agreed that people who like the title are probably not easily offended. But when Jackson arrived for shooting, the script had been neutered to garner a PG-13 rating. "They restricted my cursing and restricted the gore," he says. "It was kind of a waste of time."

As shooting continued, though, the Internet became clogged with Snakes stuff. Thousands of people were blogging, hawking T shirts and posters, composing original songs ("There has got to be much more to it/ This can't be a movie; no, it's too damn stupid/ Snakes on a Plane!" and posting exquisite fake trailers based solely on the title. The trailers, in particular, began to sketch out fans' expectations for the film. Some were mocking, but the box office doesn't discriminate between money spent ironically and earnestly, and New Line decided to ride the wave rather than be crushed by it. Five days of reshoots were ordered so that Ellis could make the movie much, much grosser. "Kids between 17 and 25 really want to see a little T. and A., so there's a nice Mile High Club scene," says Ellis. "And if you're going to do an R-rated film, you have to go for the violence and the gore. So now every time a snake strikes somebody, we hold on that snake attack and get more impact out of it."

The triumph of that populist approach is the insertion of a line of dialogue from one of the fake trailers--"I'm tired of these motherf_______ snakes on this motherf_______ plane!"--directly into Jackson's mouth. "It's kind of difficult to watch me in a movie and not hear me say motherf_______ once," he says. "I wanted to say it in Star Wars, so I'm glad we got it in here." George Lucas and other directors may bristle at the thought of an audience hijacking their unfinished product, but Ellis--who claims he has bought almost $1,000 of unofficial Snakes merchandise on the Internet--has embraced it to the point that he agreed to let New Line run a contest in which the best song inspired by the title will run over the closing credits. "I have no ego," says Ellis. "You have to be smart enough to collaborate with everybody when you're making a movie, so why not work with the people you're making the movie for?"