This begs many questions. Why has a gang of ascot-wearing, mystery-solving teens resonated with three decades of youth? What possesses nearly 2 million viewers, many of them in their 20s, to tune into "Scooby-Doo" every week on the Cartoon Network? How, indeed, did a show so formulaic, so repetitive, so ... moronic ... manage to become the longest continuously running cartoon ever?

But most importantly: What's the deal with "zoinks"?

Whenever Shaggy, the bell-bottomed hippie anti-hero of "Scooby-Doo," opened a closet door to reveal, say, the Spooky Space Kook, he'd fall back on his heels and scream, "Zoinks! " What's up with that?

It seems a simple enough question. Another direct-to-video adventure of everyone's favorite cowardly Great Dane, "Scooby-Doo and the Witch's Ghost," was released this month. For the occasion, I have access to perhaps the pre-eminent source of Scooby-Doo information, co-founder of the studio that produced him, Joseph Barbera.

But reached at the Sherman Oaks offices of Hanna-Barbera Cartoons Inc., the animator isn't so sure he can remember. He tells a couple of stories about how the series was developed, about his love of dogs, from Huckleberry Hound to Muttley, about the show's homage to Vaudeville.

And "Zoinks"?

Silence.

"Hmm," Barbera says absently. "Sorry. Can't help you there."

Hanna-Barbera was already famous for "Tom & Jerry" and "The Flintstones" when CBS approached them with the concept for "Scooby-Doo. " Fred Silverman, children's programming executive at the network, wanted some sort of mystery series involving teen-agers.

The characters _ Fred, Velma, Daphne and Shaggy _ were lifted from the popular sitcom "The Many Loves of Dobie Gillis. " Shaggy in particular resembles his inspiration, Bob Denver's Maynard G. Krebs, a beatnik who shuddered at the word "work." And no, Krebs did not say "Zoinks." The series was originally titled "Mysteries Five," after the four sleuths and their dog mascot, Too Much.

That's right, Too Much.

"It was what kids said in those days," says one of the head writers, Joe Ruby. "Like `That's too much! ' " Everyone hated the title, though. They changed it to "W-wh-oo's S-ss-scared," or something to that effect (there's disagreement as to the number of vowels). But it was Silverman who stumbled onto the infamous name, after hearing Frank Sinatra improvise "scooby-dooby doo" on "Strangers in the Night."

To the casual viewer, "Scooby-Doo" is about kids who always manage to stumble into creepy situations, like a pubescent group of Angela Lansburys. But they're really a company called Mystery Inc., sleuths-for-hire. Daphne's father even bought them that fly psychedelic van, the Mystery Machine. And when were they paid?

"That's one of those mysteries, like what Barney's job is," says Mike Lazzo, senior vice president of programming and production at the Cartoon Network.

No matter. Suffice to say, there was a reason the gang spent most of their time in scary mansions and spooky swamps. They were entrepreneurs.

It turned into an enduring venture: After the first episode of "Scooby-Doo, Where Are You? " aired in 1969, the cartoon stayed in production more or less through 1991, adding much-loathed characters like Scrappy-Doo, Yabba-Doo and Scooby-Dum.

They met the Three Stooges, Phyllis Diller and the Harlem Globetrotters. Busted the Moon Monster, Gator Ghoul and Mona Tiki Tia. Were chastised for being "meddlesome kids" in 310 episodes.

Never changed clothes.

"The motivations were very simple," Barbera says. "Scooby was cowardly, unless you gave him a Scooby snack. Shaggy was always hungry. He'd even eat plastic fruit. People could identify with them."

Let's talk about those Scooby snacks and unrelenting appetites for a minute, though. Aron Karten, a fan from Costa Mesa, thinks something else is going on here.

"You got these two stoners -- I mean, you never saw them smoke pot, but they're driving around in that van, hungry all the time," says Karten, a 25-year-old retail clerk with black-dyed hair. "C'mon."

Click on the "I Love Scooby-Doo" Web sites -- yes, they exist -- or strike up a conversation with anyone between the ages of 20-29, and the questions are likely to surface: why are Fred and Daphne always splitting off from the group? Who's hotter, Daphne or Velma? What is in a Scooby snack? These are just some of the pointless questions that keep viewers veging for hours in front of a "Scooby-Doo" marathon.

"It's something you put on and you don't have to think about it," says Stacia Hanley, 21, of Huntington Beach. "My favorite part is when Velma takes you back through the whole mystery, explains it to you. You're like, `oh, duh, I didn't notice that. ' "

She's being sarcastic, by the way.

"Scooby-Doo" is the same every single episode. Gang stumbles across mystery. Gang finds clues. Shaggy and Scooby bumble about. Plastic mask is pulled off villain. It's off to the malt shop. It's nearly impossible to tell one installment from the next.

"There's this one with this castle and a magician. I must have seen it a thousand times," says Kristin Harden, 18, of Downey. And would she watch it again? "If it was on, sure."

Lazzo, of the Cartoon Network, believes the predictability of "Scooby Doo" is part of its appeal. "It's reassuring. Formula can be a positive thing. Every year it creates a new audience, and it's fondly remembered by a couple of generations."

And though the adult subtext isn't the same as, say, the sophisticated humor of "Rocky & Bullwinkle" or "Bugs Bunny," it does give "Scooby-Doo" a comic afterlife. Heck, there are drinking games centered around its structure: drink every time Daphne is kidnapped, for instance. Karten may not be able to solve that whole Scooby snack debate, or speculate on Daphne and Fred's love life, but he does have a theory as to the show's longevity.

"It appeals to awkward, normal American kids," he says. "Growing up, there weren't a lot of shows about teen-agers. Who can't relate to a bunch of kids hanging out? I mean, `The Jetsons. ' OK, it's the family of the future -- but who wants to hang out with their family?"

Dig a little, however, and other answers emerge. In a production office in Burbank sit Joe Ruby and Ken Spears, two cartoon writers who have helped develop everything from "Captain Caveman" to "Jabberjaw" to "Thundarr the Barbarian. " They were also the original head writers on "Scooby-Doo."

From the beginning, Ruby and Spears knew they had a winner. Scooby was an instant icon. As for the plotlines ...

"Let's put it this way," Ruby says. "After we finished the second episode, we said, `Where do we go from here? ' " The answer: nowhere.

"But it works! " he says.

"You know the characters are going to run into these situations, maybe who the bad guy will be," Spear adds, "but it's how you get between the two points -- how Scooby messes up."

All right, so on to the real questions: What's with Fred and Daphne?

"Well, they were the straight characters," Ruby says, laughing.

"At first Daphne was real danger prone. But we got bored with that. " Basically, the producers got sick of writing -- and drawing -- Fred and Daphne. That's why they always split off, not to be seen until the final act. Sorry, no sexual overtones.

Ruby and Spears are less playful when it comes to the drug theories.

"No way," Spears says. The appetite was simply a funny character trait. Scooby snacks are chocolate-caramel cookies, or something close.

How about the outfits? Barbera can handle this one.

"If I was creating the show today, I'd put one of the girls in overalls. We just did what kids were wearing at the time. " And if they rarely changed styles, it's because the characters had become so recognizable -- and anyway, bell-bottoms are back.

(Thank goodness ascots haven't returned, though).

"It amazes us to think that it's lasted this long," Spears says. "These things come along once in a lifetime. It's amazing -- our grandchildren watch the show. Who could have guessed?"

Fair enough. But "Zoinks"?

"We were very cognizant of creating catch phrases back then," Ruby says. Fred Flintstone, after all, was famous in no small part because of "Yabba-dabba-doo," a play off of "Yahoo! " For Daphne, then, it was "Jeepers! " which was already in the vernacular, as in "Jeepers creepers! " For Velma, it was "Jinkies," which was invented by a writer during a brainstorming session, basically a take-off of "high-jinks."

And "Zoinks? " Silence.

"Someone just said it," Ruby says.

"Not sure where it came from," Spears adds.

"No idea," Lazzo says.

Perhaps it's a mystery not even Scooby can solve. I wouldn't be so bothered by it, either, if it weren't for those meddlesome kids.