The World According to Garth

Sometimes Brooks gets more than he bargained for. One night, a woman in the audience got so caught up in his stage persona that she yelled, ''I'll give you $500 to (let me perform oral sex).''

Backstage after the Tulsa concert, the energy level has come way down and the Garth fans have split into groups, each with its own agenda. A bevy of young women with Instamatics stands anxiously in one corner, waiting for a glimpse of the star. A clot of middle-aged women with Marine haircuts slug each other on the arm and wait for Garth's bass-playing half-sister, Betsy Smittle. In his dressing room, an older woman is telling Garth, ''I've never had a hero or an idol. But you make me believe that good still exists.''

Yet not everyone is having the time of her life. Over in yet another corner backstage, the soft-spoken Sandy Brooks is keeping a low profile, talking with her mama. At 1 a.m., she's hoping everyone will go home so she'll have 45 minutes alone with her husband, who will leave for South Dakota the next day while she'll go home to Nashville. Even though she trusts him with women on the road, she can't help but worry about them, too.

In a way, their relationship seems curious. He hauled her up on-stage with him to accept the Country Music Association's Horizon Award last year, and praises her in interviews — tells everybody that it was Sandy who kept him going by working three jobs and refusing to move back to Oklahoma when at first Nashville rejected him. Yet he all but says that when they married in 1986, he was apparently more interested in how she could help him achieve his dream than what really mattered to her. The most important person in his life, he admits, is his brother (and road accountant) Kelly, an attachment he says Sandy has learned to accept. ''I love my wife to death, but Kelly and I should have been Siamese twins.''

In 1989, Sandy almost left her husband because they never had any time together. Since he's been on the road, ''it's almost like we've both had to learn to live separate lives,'' she says, a discernible lump in her throat. Beginning in mid-December, Brooks will take six months off the road to write and to get reacquainted with his wife. They have a big new house in Nashville for which they'll buy furniture when he comes home.

Both Brooks and his wife know that personal sacrifices are all part of launching a career. On the whole, Garth says, ''This is a rush like I never dreamed music would be.'' Then, in the next breath, he talks about how scared he is that it'll all end tomorrow. He knows he could please the powers that be in Nashville by playing it safe — steering away from controversy and never veering too left of center. But, there's that little kid inside of him that can't resist pushing things to the limit and ignoring the danger signs — sticking his fingers in the fan.

''Ultimately,'' says Sandy Brooks, ''Garth wants to be able to sit back and say, 'Yes, I did it. I did it my way, and I had a hell of a lot of fun.'''

At the least, the fat boy is on his way.