It's easy to pick out a real Cyndi Lauper fan. She's the screaming preteen girl wearing smeared purple lipstick, and a bright pink ribbon in her electric orange and green hair. If she happens to be humming a tune, it's probably one of Miss Lauper's teeny-bopper hits, ''Time After Time,'' ''She's So Unusual,'' or ''Girls Just Wanna Have Fun.''
Of course, not everyone at the Sunday night Concert on the Common had loose, drip-painted clothes or green hair. As one of her other audience (male, mono-colored hair, ''normal'' clothes), I was mildly amused by Lauper's deliberately jerky dancing and her squeaky voice. And I found her music - a hodgepodge of pop styles - lively.
But to her young fans, she was much more than a comedienne or musician. Aside from dressing just like her, they brought her flowers and dolls and carried a torn-sheet banner that read, ''Cyndi Lauper, we love you.''
I think the reason Lauper's career has skyrocketed over the last year or so is that, in her childishness and innocence, she fulfills a need for childhood in her young audience. In fact, her biggest hit, ''Girls Just Wanna Have Fun,'' could be seen as an anthem for a generation of young people whose childhood has been taken too soon. In a time of high divorce rates, latchkey children, and designer jeans, Lauper encourages kids to throw away adult things for a while, dress up outrageously, and dance as awkwardly as they want.
If she is to be more than a passing fad, however, she'll have to become a more varied and - I hate to say it - mature musician.But in the meantime, she's one of the more positive of today's pop stars.