But then, out of nowhere, on the last day of June, came a whizz-bang speedboat, zigging and zagging through the stupid fleet, with a bomb in its prow. Insolent, raunchy, breathtakingly offensive, it's not just the movie of the season but the most truly radical American movie in years, the talking point at cocktail parties, and an event at which kids are jumping up and down like freed slaves while elders groan and clutch their heads against the pain that will not go away. Above all, this mongrel, whiplash movie has made a mockery of the whole question, "What is a kid?" And it's called South Park: Bigger, Larger & Uncut.
"Oh, South Park," you still hear some adults say patronisingly. "That's the cartoon for grown-ups, isn't it?" Attend to those lofty folk, for if they have children they are riding for a fall. South Park already airs in Britain, on Channel 4 and Sky One, so some of you may have made this journey already with a cartoon that few adults are strong enough to take.
What do you expect if the cartoon in question is drawn about as well as the average eight-year-old can draw, and if it has for heroes four vacant-eyed blobs in the American third grade? The blobs live in South Park, Colorado - have done for several years now, since long before the bewildered, inane guilt and helplessness of American parents was triggered into alarm by the Columbine High School massacre in the Colorado town of Littleton. South Park is referred to in the movie as a "quiet little red-neck Podunk white-trash mountain town". And who could be amazed if this fictional locale was one of the favourite escapes of alienated kids in a place like Littleton, who thought that parents, school, the President, the nation, its hypocrisy, its wealth, its greed, its miserable education and its TV diet every day sucked - like the sound of the bath water running out?
I don't know if there's a proven Littleton connection, but if you realise that American kids have been watching five, six, seven, eight or more hours of TV every day, without guidance or discussion, it's a fair supposition. And since that tragic day in April, the American parental class has all of a sudden become very anxious about this state of affairs. In countless articles and around countless dinner tables, it has blamed TV and the movies as a vague generality, and it has cast around for some silly and apparently practical thing to do.
The American "R" rating is the begging target. It is the self-regulating practice of the country's movie business to rate its films as a guide to parents. The scale goes as follows: G (anyone can see this - if they've got nothing else to do); PG (parents should think about this): PG-13 (they should really think about this if their kids are under 13); R (no one admitted under the age of 17 unless accompanied by a parent or adult guardian); and NC-17 (no one under the age of 17 admitted).
This system and its practice have been a disgrace, a face-saving way of allowing the industry to make as much money as possible while shrugging off responsibility. What it means, in daily business, is that kids under 13 can get into PG-13 pictures if they say their parents thought about it - if asked. Further, kids under 17 (which means kids of six, five, four, three - just so long as their whimpering doesn't disturb the adult experience), if they are "with" adults, can see Eyes Wide Shut, Saving Private Ryan, Psycho, Taxi Driver - just about any movie ever made.
This crazy state of affairs has arisen because NC-17 is a virtually unoccupied rating in America. In many parts of the country, there are local laws that forbid the showing or publicising of NC-17 films, and so the industry regards that rating as commercial death - instead of a legitimate form for material and issues that require mature participation from the audience. The contract that film directors now sign orders that a completed film must obtain an R rating - and they are compelled to make the cuts deemed necessary to get it.
In practice, this hypocritical and damaging policy has been held in such contempt by theatre staff that they hardly bothered to screen out kids who didn't have an adult with them. But rather than respond with horror and grief to the built-in iniquity of the R rating, the American parental class (post-Littleton) has jumped on the need for "proper" enforcement. And so, when I took my nine-year-old son to see South Park at a cinema in San Francisco, I was asked at the box office whether I was indeed taking my son with me - and at the entrance to the theatre itself, there were staff poised to question anyone of borderline age. One 13-year-old was barred from admission: he said his mother had bought him his ticket, and that she was "downstairs somewhere". We will see how long this novel vigilance lasts.
More to the point, with the genius of a Picasso or Stravinsky sensing new forms, Trey Parker, the man behind South Park, has made the R rating a plot point in the new film - and clearly that decision was taken months ago, before the events at Columbine, when the R was simply an outrage to any sane American.
For in Bigger, Larger & Uncut, the South Park cinema plays a "depraved" Canadian film (this deadpan oxymoron is typical of Parker's humour) starring "Terrance and Phillip", a foul-mouthed duo. The four blobs get into the film by paying a homeless person to be their moral guardian. They rejoice at the language of the film - "Shut your fucking face, uncle fucker" is one song. Later on, they pick up that eternal riddle in life: "What's the clitoris?" In the movie, the US responds to the Canadian immorality by declaring war on its neighbour and bombing it into the condition of Kosovo.
There is also a flagrant gay affair going on between the Devil and Saddam Hussein. And before the film is over, the clitoral quest is, if not quite answered, augmented by the sight of a vast pink bombe surprise rendering of the little rosebud itself.
These things are not easy to write about. Readers of The Independent may feel they have a right to be spared. But I believe that's what Trey Parker wants to have us start thinking about. You may be shocked to hear that I took my nine-year-old to the film. My reasons were as follows: though nine, he is a devotee of the TV series (where the language is bleeped in America), who educated his parents in seeing its satire and its politics; though nine, he will only get older - we have found no way to arrest his development; though nine, he has heard adults - his parents even - use the word "fuck", and there is no way of asking the jury in him to forget the word; and, though nine, when he asked what the clitoris was, or what it was for, he listened carefully to our answers, was tolerant of our shyness and ineptness, but learned. We talked about the film for a solid hour - and we all learned a good deal about what adults and children think, know, pretend to know, and try to ignore. We were a family.
You have every right to keep your nine-year-old from seeing South Park when it opens on 27 August in Britain. Indeed, the BBFC's 15 certificate keeps young children out of films - and South Park will surely be awarded a 15. In America, I might add, it nearly got an NC-17. But the most vital point raised by this mischievous, but very sane, film - when it comes to the impact of actually watching it on the screen - is that no one really sees anything "with" anyone else. We are alone in the dark. Which makes it essential that we talk about what we have seen as if it were a matter of life and death. In Colorado, it has been.