GINA SCHOCK leans over the lounge table, pretending to be an intrepid reporter. Across from her, Belinda Carlisle scrunches up her baby-fattish face and waits for The Inevitable Question. "What's it like to be a girl in an all-girl band?" A split second later, they're both howling.

"And then there's 'How do your parents feel?' " Carlisle adds, petulantly. "How would your parents feel? How would anybody's parents feel? They never ask the boys!"

Until recently, there were few women to ask about the effects of rock 'n' roll success; most have been typecast as singers. Until the Go-Go's. Schock is the drummer; Carlisle's the lead singer. Since the birth of rock 'n' roll in the mid-'50s, no self-contained female band has ever had a No. 1 album; the Go-Go's, most of whom couldn't even play their instruments when they came together in 1978, did it with their debut album, "Beauty and the Beat," while their follow-up, "Vacation," nestled last week at No. 5.

"We always thought if 'Beauty and the Beat' sold even 100,000 copies, we'd be real happy and a successful group, so when it reached a million . . . " Schock stops in shock and starts chuckling. "Hey, we just laughed about it. What are you gonna do? It's craaaa-zy."

Schock, Carlisle, bassist Kathy Valentine, lead guitarist Charlotte Caffey and rhythm guitarist Jane Weidlin are all in their mid-twenties. Since they hit the charts, and the headlines, they've developed a certain harmony in their coltish responses to press queries. Schock and Carlisle have a disconcerting habit of finishing each other's thoughts, or worse, saying the last three or four words of a sentence in tandem.

And the energetic, surprisingly innocent interaction of the Go-Go's' stage show extends offstage. Despite their ages, the five women can slip into nerve-wracking girlishness at the drop of a hem, a distaff variation on the perpetual adolescence inherent to rock. Carlisle: "I like 'girl' better than 'women'; it makes us sound younger." Schock: "I just don't like to be called a 'woman' or a 'lady' because I don't feel like either a woman or a lady. I feel like a musician." Carlisle: "But 'girl' sounds more like what we are, like teen-agers." Schock: "Will you shut up and lemme finish! Butt out, wom!").

Physically and emotionally, Schock and Carlisle are as different as the coasts they come from. Carlisle is the prototype Valley Girl, a one-time cheerleader for Newbury Park High in Thousand Oaks, a well-to-do Los Angeles suburb. Like many of her compatriots, she was fascinated with the teeming punk scene in L.A., dyeing her hair with peacock passion and almost joining a hard-core punk group called the Germs.

Schock, the daughter of a longshoreman, is all-Baltimore--tiny, wiry, direct and outspoken in that peculiarly lively "Balmer" dialect. She's the most experienced musician in the band, 12 years of drumming inspired by her hometown's fascination with hard, blue-collar rock and heavy metal. As a teen-ager, she'd buy new drumheads instead of clothes, rushing home from school to don headphones and thunder along with worn-out records. Schock made her first trip to L.A. in a band with the massive Edith Massey of John Waters film fame. She met up with the Go-Go's in 1979.

The Go-Go's had started in Los Angeles in 1978 as a reaction to the amateur esthetic prevalent on the punk and New Wave scene. The women's response: "Anything they can do, we can do." The "better" part would come later. Down the line punk predeliction became pop realization. "We always wanted to be a pop band; we just didn't have the ability at the time," says Carlisle. "It evolved as we became technically able with our instruments."

"I prefer to call it a rock and roll band myself," Schock interjects.

"Or pop-rock," Carlisle offers. "It's a combination."

"Yeah, but I've always hated pop music."

"I've always loved pop music!" Carlisle shoots back.

"So THERE, YOU KNOW?" The drummer always gets the last beat.

"I thought the band had a lot of potential," Schock says. ("Gina, don't scratch your forehead," Carlisle whispers as Schock talks; "you'll get worry lines. Okay?") "I thought their songs were good and that they had good harmonies. The only problem was that they couldn't . . . execute . . . their songs properly, couldn't play their instruments that well Weidlin had to number the frets on her guitar to learn chords . But they had the makings of a really good group, which is why I joined. And it was fun, too."

With Schock and Valentine providing a tough rhythmic bottom, The Go-Go's started playing the club circuit, building up a following with infectiously bouncy music that wedded ebullient girl-group harmonies to the big beat of the Ventures (in fact, they wrote a song, "Surfin' and Spyin', " that helped revive the Ventures' stateside career). There had been other all-girl bands, of course; L.A. had already seen Fanny, Birtha, the GTOS, Runaways and Orchids. And bassist Valentine has been in an earlier version of Girlschool, an all-girl heavy metal outfit from England that has since become quite popular.

They admit to myriad influences (though they disassociate themselves from the '60s girl groups), and to very specific likes and dislikes: They all love Roxy Music and David Bowie, while "the only thing that all five of us do not like is jazz-fusion," according to Carlisle. Schock had been weaned on Led Zeppelin, Valentine on the Stones and Texas r'n'b, Weidlin and Carlisle on punk, Caffey on the Beatles. The resulting amalgam was pure rock 'n' roll in the rhythm section and pure pop in the vocals, with the "girl group" sound surfacing only in the harmonies. And the whole thing was dressed up in vividly colorful thrift-shop finery.

Despite some rocky on-the-job training, good word-of-mouth started spreading and the Go-Go's were eventually signed to the small, independent IRS label; the traditionally myopic major labels had passed, not noticing the band's confident power pop and choosing to write them off as a novelty act. Still, there was serious consideration given to omitting the group's picture from the cover of "Beauty and the Beat," to obscuring their gender in hopes of sneaking it past radio programmers.

The album was slow to take off; in fact, "Beauty and the Beat's" climb to No. 1 was one of the slowest in history (six months). Once the dice started tumbling right, they tumbled fast: In Washington, for instance, the band moved from the 9:30 club to the Capital Centre (opening for the Police) in less than six months; a week ago, they drew 12,000 screaming fans to the Merriweather Post Pavilion. And they received that peculiar rock accolade of being on the cover of Rolling Stone in their underwear.

The underwear pose was a bit of chance-taking for a group that has not only overcome but turned sexual-musical sterotypes around. "Only photographer Annie Liebowitz could have talked us into that. At first we said, no way, but she convinced us," Schock says. "And we'd never done anything like that so it was about time." The band was less pleased with the magazine's cover headline, "The Go-Go's Put Out." "I was upset about that," Schock continues, "but on the other hand I felt privileged to be on the cover of Rolling Stone. Since I was a child that was one of the pinnacles of success. That and playing at Largo."

With 3 million copies of their debut album sold, things have changed a bit, of course. Now, each Go-Go sleeps in a separate hotel suite; no more doubling up, except in laughter.And the spotlight shines a bit more directly, particularly on Carlisle, who is a regular item in California gossip columns (she is now dating a Los Angeles Dodger).

Jane Weidlin wanders into the hotel lounge and Carlisle and Schock are riveted in their seats. "Jane has a new hairdo! She looks like Buckwheat!" They fall apart laughing, though Schock stops when Carlisle mentions that she's starting acting school in December. "Oh, you are?" she says incredulously.

"I got it all straightened out. I didn't tell you that? Hopefully in 10 years, I can have a career in the Go-Go's but I can also settle down somewhat."

"Honey, if you're going to act, you ain't nowhere near settling down," Schock says. "You know what a horrible schedule that would be? Just think about it, you go out to Siberia and shoot for eight months . . . "

There is a bit of concern, lighthearted for now, about the future. On the one hand, the women describe themselves as "driven, determined people" . . . "But we can't see ourselves being 40 years old jumping around stage in our miniskirts," Schock points out. "As long as it's fun, that's most important. The only problem is, that the musicians, the guys, their careers can go from the time they're 18 till they're 50 years old and when they get wrinkles, they're 'character lines.' But when girls get 'em, they're WRINKLES!"

Adds Carlisle, "The only thing I worry about is will people want to look at us?"

"Yeah, will they look at these fat old bags?"

They are still cautious--wrecking a dressing room and then cleaning it up; they can't think about throwing televisions out hotel room windows yet, mostly "because we're on a budget," Schock insists. "Though I think we'll be driven to that at some point."

The Go-Go's had their first real vacation in almost two years in July, just as "Vacation" was hitting the stores. Any differences? Says Schock, who came back to the Bay area, "I still enjoy fishing and crabbing. But now we can afford to rent jet skis and sailboats."