The season's most popular novelty is a pocket-size electronic voice box that, at the push of a button, spews profane insults suitable for use in locker rooms, saloons and stockbrokers' offices.

This adult toy is called the Final Word, and it delivers prerecorded obscenities in a shrill voice that sounds like an angry chipmunk from Brooklyn."They're flying out the door," said Joan Geisler, owner of Postermat in Greenwich Village, as she waited for a broker to pick up his order of 60. "People are calling up and reserving them by the dozens." Uptown, Dapy's on Columbus Avenue reported selling more than 250 in two days.

The Final Word, which sells for $16.95, is a battery-powered, pre-programmed voice synthesizer that looks something like a beeper and sounds something like Andrew Dice Clay. It is designed to appeal to people who like the sound of dirty words but may be reluctant to actually speak them.

The Final Word, according to its manufacturer, allows people to talk back to "all those obnoxious people in life, such as nagging in-laws, pushy salespeople and know-it-all bosses." All of whom, no doubt, have already purchased their own Final Word.

The device comes in two versions, one rated "G," the other "X." The former repeats these phrases: "You're an idiot"; "Drop dead"; "You're a dope"; and "Stupid jerk."

The content of the other version cannot be repeated here. Care to guess which of the two sells better?

Once buyers hear the stronger version, "they've got to have it," chortled Geisler, who has taken to using the X-rated version extensively over the telephone.