SIT-DOWN COMEDY

''Attention spans are getting so short it's a little frightening,'' writes Rita Rudner. ''People don't even read books anymore. They just like short, funny essays where the subject changes every three minutes.'' If Rudner is correct, people are going to like Naked Beneath My Clothes, the comedian-turned- writer's collection of bite-size meditations on love, family, food, and even fashion. Rudner's writing spoofs the needlepoint epigrams of Robert Fulghum and Erma Bombeck and puts a dent in the self-help genre. Like her stand-up act, honed over years of talk shows and cable specials (Born to Be Mild), Rudner's book offers more observations than punch lines. ''I don't laugh at jokes,'' Rudner says. ''I laugh at people, kids, dogs, life, everything.'' In fact, Naked Beneath My Clothes marks the beginning of a career shift away from stand-up. What inspired her to take pen in hand? She laughs. ''Is it terrible to say it was an advance? I love writing, but I wouldn't dare write a novel. I had never thought of a book at all,'' she says. ''I live in Hollywood. They write screenplays there.'' And Rudner is no exception. This November will bring the release of Peter's Friends, a comedy directed by Kenneth Branagh from a script by Rudner and her husband, British comedy producer Martin Bergman. ''It's about six friends and their husbands and wives who get together for a huge New Year's Eve weekend,'' she says. ''Ken directed and produced and starred. That didn't stop us from being mouthy with our opinions.'' The film has already gotten Rudner and Bergman another job offer-a rewrite for Disney-but she's taking nothing for granted. ''You know, Hollywood kills you with hope,'' she says. ''To have actually made something and like it is more than most people ever get to say.''