NBC programming chief Brandon Tartikoff, currently broadcasting's fair-haired tot, apparently feels the need to prove his fallibility. No one doubted it for an instant, but if he had to reaffirm it, he could have done so without stooping quite so low as "You Again," a dismally dumb domestic sitcom that gets a cat-bird's-seat premiere at 8:30 tonight on Channel 4, right after "The Cosby Show." Then it moves to Mondays at 8, where presumably it will die the good death it deserves.

Jack Klugman, as gratingly obnoxious as ever, plays a bellicose oaf who has been divorced for seven years and whose son, now 17, decides to move in with him after being in the custody of the mother. A viewer's first reaction upon meeting these two unpleasant buffoons is that this unseen wife and mother is a wise, wise woman indeed. We admire her in her wisdom. We want to join her in her wisdom.

The pilot, which is a cracked monument to television worthlessness, predicates itself on that oft-exploited anxiety of sorry sitcoms everywhere, a parent's fear that a daughter has become pregnant or, in this case, that a son has impregnated a young woman out of wedlock. As usual in such shows, no mention is ever made of the fact that simple birth control procedures can prevent such unfortunate occurrences. The subject is played for pea-brained titillation and nothing more.

Matthew, the son, is played by John Stamos, the one-time soapthrob who bombed last year in the CBS sitcom "Dreams." He is not without a certain petulant charm, but here he has to try to one-up, or one-down, the thuggish Klugman. The premises are further cluttered with Element No. 523-B from the Comedy Night School Handbook of Lame Ideas: a saucy British housekeeper, played coldly by Elizabeth Bennett.

In short, a drearier household of bores and banalities would be hard to fabricate -- not that somebody won't.

The young woman whom the son brings home in the premiere is a punk princess in garish makeup and spiked hair; that gives writer Eric Chappell the excuse for plenty of insult humor from Dad, who refers to the girl as a freak, a ghoul, the Wicked Witch of the West and the Bride of Frankenstein. There isn't one real laugh in the whole show.

Chappell also wrote the British comedy "Home to Roost," on which this show was based; it had to be better. Peter Bonerz, the director, apparently tried to keep his distance, and who can blame him? Knee-slappers in the script include Klugman making a finger gesture meant to represent sexual intercourse and this exchange between father and son: The son says, "I'm a love child," and the father says, "There's nothing lovable about you." Neither is there about "You Again."