The Barenaked Ladies have an important message for the world:

Enough, already, with the macaroni and cheese!

The band's fans ritualistically pelt the Ladies with macaroni and cheese at a certain point in almost every concert. Yes, cooked. Slimy. Smelly. In a way, the Canadian rockers brought it on themselves: You see, they have always put on a, well, interactive show, with a lot of improvisation and give-and-take with the audience.

The periodic cheese storms occur at the high point of one of the band's best-loved songs, "If I Had $1,000,000," which details the goofy get-rich fantasies of adolescent slackers, with vocalists Ed Robertson and Steven Page singing alternate lines:

If I had a million dollars

We wouldn't have to walk to the store

If I had a million dollars

We'd take a limousine 'cause it costs more

If I had a million dollars

We wouldn't have to eat Kraft dinners--

But we WOULD eat Kraft dinners

Of course we would--we'd just eat more!

(And buy really expensive ketchups with it)

(Yeah, all the finest . . . Dijon ketchups!)

So fans have been tossing macaroni and cheese onstage whenever that verse is sung--and have been doing so since 1992. Now bass player Jim Creeggan says it's time to stop.

"I get too much cheese inside my bass," he complains. "It's not very easy to clear [that] out of it."

After all, this is not the plucky clutch of smart rockers who captured the hearts of Canadian music fans in the early 1990s, went off to conquer the States--and suffered as two subsequent albums failed to catch on. Now they are ending the decade by actually accomplishing their goal with the 1998 hit "One Week," a silly, hip-hoppy lightweight that seems to have been memorized by middle schoolers from sea to shining sea. They're closing in on 4 million copies of the album that "One Week" appears on, "Stunt," and tomorrow will perform a sold-out concert at Merriweather Post Pavilion.

Part of their appeal is that the Barenaked Ladies look like regular guys. They run the morphological gamut: Drummer Tyler Stewart is so chunky and bassist Creeggan so scrawny that one of the regular riffs onstage is for Robertson to stand the two men side by side and announce, "Ladies and gentlemen, today 'Sesame Street' is brought to you by the letter O and the number 1!" It's all part of the antic humor of their live gigs, in which they are wont to break into comic monologues, loony dances, improvised songs about whatever strikes them--say, the toiletries provided in their hotel rooms--in other words, happy chaos. With a beat.

They formed in 1988, intentionally taking on an absurd name that evoked the wide-eyed, goofy adolescent persona of many of their early songs. Creeggan draws out the phrase in explanation: " 'Bare, naked ladies!'--just sort of conjures the kid mentality, the kid head-space of being excited about something mysterious," wondrously whispered, with its poorly understood intimations of sex.

The promising 1992 debut album, "Gordon," was a trove of startlingly innovative songs with rich, clever lyrics, including "Grade 9," a perfect-pitch re-creation of the first days of school and the insecurities of adolescence:

Well, half my friends are crazy and the others are depressed

And none of them can help me study for my math test

I got into the classroom and my knowledge was gone;

I guess I should have studied instead of watching "Wrath of Khan."

The album sold hundreds of thousands of copies . . . in Canada. That market became saturated, yet Barenaked Ladies remained largely unknown below the 49th parallel. Page says the band members made enough money to buy decent houses for themselves, but their next two records didn't sell well--which almost certainly made it a struggle to keep the sense of humor that made the first album so engaging. It still shows through, however, in songs like "These Apples," which jokingly depicts a doomed relationship. She's sentimental, and he's an inarticulate yutz: So enthusiastic, a little bit drastic, I shaved her name in my head/ And as she beheld it, she said I misspelled it; need more be said?

Other early songs, though, show a brooding sensibility and a fascination with the dark corners of the mind. In "When I Fall," a window washer has developed a fear of heights; the gut-churning rocker "The Old Apartment" is narrated by a creep who comes back to his former haunt to terrorize his ex-girlfriend. And then there's "Straw Hat and Old Dirty Hank," about an obsessive fan stalking a female singer.

"I'm a relatively dark person sometimes, but I have a sense of humor about the fact that I can be a dark person," says Page, who writes many of the songs and sings with a voice as smoothly modulated as a muted trumpet. "I think most people, if you stand on the roof of a building . . . have a voice that says, 'What if I jumped off?' "

"I write about it rather than doing it."

He's the kind of guy who, when asked about his favorite authors, cites Philip Roth, John Updike and Saul Bellow--"The ornery bastards. Like the Randy Newmans of literature." Newman, the crotchety singer-songwriter who also explores the angry and the odd in his musical personae, is a big favorite of Page's as well.

The band began the climb back with "Rock Spectacle," a live album that pulled the best of the earlier songs into a collection that also captured some of the manic pleasures of their performances. But even as they climbed, trouble struck again; keyboard player Kevin Hearn developed leukemia and had to take a leave of absence.

And then "Stunt" turned out to be a monster. And Hearn responded well to treatment and is now considered cancer-free; he is playing with the band on this tour. "It's such an amazing change to have him back in the fold," Page says with relief. "It really feels like our band's back."

"One Week," though, was such an overplayed hit that the band went from being relatively unknown to widely disliked. "It used to be, 'I don't like this band, and I'm glad they're not popular,' " says Page. "Now it's 'I don't like this band, and I don't understand why they're popular.' It's okay. We're not for everybody."

Other musicians tend to dis the band as well; rapper-folkie Everlast recently slammed it as "the corniest [expletive] ever. They're like the worst example of what hip-hop and rock blended does."

Page admits "One Week" is "definitely a novelty song"--the derogatory industry phrase for ear-catching, funny, but lightweight--like "Who Shot JR?" and dogs barking "Jingle Bells." Page defends it, sort of: "I don't feel like that's less than our good stuff."

Some songs express your deepest thoughts and feelings, and are valued by discriminating listeners; others sell a few million copies. It all works out in the end.

Fans keep up with the Ladies via the Internet, posting Web pages and chatting about it online. Though Robertson has entered the discussions to talk about his songs, Page says he's stopped surfing with the fans. "When you're an artist and you've put a record out and you've spent six months living and eating and breathing it--and I look on the Internet and they're saying, 'This is [expletive],' or 'Okay, it's all right, maybe it's my number two favorite' . . .

"It would just bother me too much," he explains. Now he looks to feedback from the people at the concerts--the ones screaming and jumping in front of the stage. "I believe that the Internet doesn't really exist," he jokes. "It's just a thousand people living in Montana feeding things into my computer."

CAPTION: Ed Robertson, left, Tyler Stewart, Jim Creeggan, Kevin Hearn and Steven Page are the Barenaked Ladies.

CAPTION: Ed Robertson, above, and Jim Creeggan, below. The Canadian quintet has seen its fortunes soar with the success of the song "One Week."