Somewhere out there in the cinematic ether there's an elusive line between lewdly moronic raunch comedies like "Tomcats" or "Freddy Got Fingered" and sophomoric, low-brow sex and gross-out romps that can make even intellectual types laugh until $3 concession Coca-Cola comes out of their noses.

I don't know where that line is exactly. All I know is that "Jay & Silent Bob Strike Back" is hilarious.

The latest low-budget, high-dialogue laffer from Kevin Smith -- writer-director of "Clerks," "Mallrats," "Chasing Amy" and "Dogma" -- this film puts his perennial cameo characters front and center for a combination road-trip/ruthless Hollywood satire that is so blanketed with ribald raillery it feels like machine-gun fire hitting your funny bone.

Jay and Silent Bob (played by Jason Mewes and Smith himself) are vulgar yet somehow endearing, dimwitted bakeheads and convenience store loiterers who have appeared in all five of Smith's New Jersey-based comedies, in which he frequently mixes base humor with surprising social insightfulness.

Until becoming major supporting characters in 1999's controversial Catholicism diatribe "Dogma," they'd only popped in one scene per picture. In "Chasing Amy," for example, they met cartoonist Ben Affleck in a diner to collect royalties from a tongue-in-cheek superhero comic book he based on them called "Bluntman and Chronic."

In "Jay and Silent Bob," Miramax is making a major motion picture from that comic book, and our heroes are on a cross-country crusade to stop them -- or to at least secure a cut of the box office grosses.

Although it's jam-packed with Smith flick in-jokes, movie spoofs, cameos and showbiz digs, the story itself is pretty hackneyed and elementary. Jay and Bob unknowingly hitch a ride to Hollywood with a foursome of sexpot jewel thieves who plan to use them as fall guys for a diamond heist in Colorado. They spend the first act trying to get into the girls' leather catsuits and the second act on the run from inept lawmen, led by Will Ferrell and Judd Nelson.

But the simplistic plot is just a backdrop for Smith's constant comical commentary that includes everything from a side-splitting, sexualized "Scooby-Doo" spoof to a shoe-string budget version of the "Charlie's Angels" break-in scene to self-referential rants about the rabid internet rumor mill regarding this very movie.

Unlike the higher-minded "Dogma" and "Amy," which used humor to cloak sincere statements about religion and sexual insecurity, "Jay and Silent Bob Strike Back" doesn't aspire to be anything more than base-comedy burlesque. It's dumb, dumb, dumb and crass, crass, crass -- but funny, funny, funny.

Right out of the gate, Smith takes pot shots at the movie industry, even leveling some ire at Miramax Films, distributor of all his films (including this one) except for "Dogma," which was sold to Lion's Gate when the picture became a political hot potato. But when Jay and Bob finally reach Tinsel Town in the third act, the industry japes really kick in, with self-mocking cameos galore (Mark Hamill, Chris Rock, Shannen Doherty and Wes Craven, to name a few).

One of the funniest scenes in the movie sees Jay and Bob breaking onto the Miramax lot and becoming extras in the gun-toting revenge thriller "Good Will Hunting 2: Hunting Season" (Matt Damon and Ben Affleck, Gus Van Sant) before being chased by security guards through episodes that parody "Scream," "E.T." and "Pee Wee's Big Adventure" almost simultaneously.

By the time Jay and Bob finally reach the "Bluntman and Chronic" set, Smith is going 100 mph with the slapsticky lampoonery and can't seem to find the breaks. It's as if he was determined to pack ever single movie-making joke he'd ever conceived into the last 30 minutes of this picture, and somewhere along the line he trips over his own sarcastic gags, falling into a finale of clichés as lame as those he mocks only moments before.

But the ratio of sore-cheek zingers to comedy duds is so high throughout the picture that it's easy to forgive Smith for losing control at the end. Not only does "Jay and Silent Bob" keep you laughing, but in its immaturity it demonstrates, ironically, a certain aptitude Smith has acquired to as a filmmaker. Making a movie this fatuous without insulting the intelligence of the audience is quite a feat.