The Wild Girls Club: Tales from Below the Belt

With the publication of The Wild Girls Club, Detailsmagazine columnist Anka Radakovich, 29, joins the growing ranks of feisty female sex writers, pushing the envelope every panting step of the way. Her occasional schoolyard euphemisms (''hooters,'' ''tubesteak'') notwithstanding, Radakovich has wit to burn and uses it to describe her ''research,'' which included a date with a gigolo; calls to a phone sex line; visits to a matchmaker and a nudist colony; experiments with aphrodisiacs; and ''road tests'' of assorted condoms. The Cynthia Heimel of the slacker set, she's smart and progressive-and her book, The Wild Girls Club: Tales From Below the Belt, should have closed on page 187, where her columns end and her vapid interviews with fringe celebrities begin. A-