Blunt, earthy, nuts-and-bolts talk about sex--in the spirit of ""Dr. Ruth's"" popular phone-in N.Y. radio show. (She'll soon be on national TV too.) A sex educator and therapist, Westheimer believes in spelling it out for the home-folks. Her bywords are ""talk,"" ""experiment,"" and ""use contraceptives."" (""My boyfriend and I are getting into whips and chains,"" a young girl confides on the air. ""With contraceptives?"" Westheimer wants to know.) For each topic, questions-and-answers precede a more expansive discussion--of touch, foreplay, afterglow, positions, diseases, teenagers, gays, the elderly, the disabled. ""I have no patience with people who tell me they are too tired to touch their partners,"" Westheimer snaps; even if you're too fatigued for sex, you can cuddle or ""masturbate"" your partner. Talking is important too; she made a silent accountant more ""soulful"" by teaching him to lean against his wife and sigh. Sticking exclusively to old routines--including the missionary position--is a definite no-no. (If you can't stand performing fellatio, try to imagine you're eating an ice cream cone--""But don't tell your husband."") Westheimer also worries about older couples who eliminate sex from their lives unnecessarily: men may no longer be able to achieve a ""psychogenic"" erection, but that just means they need more direct stimulation (and they can, she avers, maintain an erection for a longer time). Teenagers are told they shouldn't feel pressured into sex, or into losing their virginity on principle. Condoms and diaphragms are talked up as against the Pill, etc. An opinionated personality item, primarily for old and prospective fans--best supplemented with a balanced guide like Crenshaw's, below.