No one cares about fussy things like 'like' any more," my friend in advertising exclaimed, a bit touchy. I had challenged the grammar of a line she had written for a client: "Nobody knows, like Domino's, how you like pizza at home."

"Of course people care," I insisted, remembering how purists boiled up in anger over the aggressively colloquial 1954 commercial declaring that "Winston Tastes Good, Like a Cigarette should." But that was a generation of purists ago. My friend in advertising turned out to be right about modern language. The Domino's ad appeared on national television hundreds of times last winter and elicited no outrage, no controversy, not one complaint.

Why? In a time of ever-longer schooling, why does American English usage seem to be degenerating? Because we are seeing, right before our ears, the triumph of Spoken English over Written English. Indeed it is a triumph so complete that defending formal forms risks looking prissy.

For much of America's history, written English established the national norm. Letters, books, newspapers, periodicals, telegrams -- these were the methods of general communication. And people did more than communicate with written language. They flaunted their verbal virtuosity with big words and starchy grammar. Spelling counted. To be caught in "accomodate" or "harrass" was to look unlettered, uncouth.

Spoken language, on the other hand, has no spelling, and as for grammar, the principal rule is simple: "Does it sound right?" By phone and phonograph, the tongue tide soon spread, eventually reaching full flood with the advent of talkies, radio, tape and television. These days, like it or not, there's no point in singling out the Domino's commercial; everyone seems to misuse "like," if only to sound right. A cable TV ad for Showtime promises that "We entertain you like no one can." An Op-Ed writer declares in The Times, "Like I was saying, New York is the greatest city in the world." Writers uncertain of when to use "like" (to introduce a noun not followed by a verb) regularly duck behind clumsy evasions like "such as."

"Like" is just one example. Casual spoken usage infects formal usage in many ways -- like the split infinitive. English teachers can't credibly urge that it be used with discrimination, not when their students' Star Trekked ears discern no fault in "to boldly go where no one [ originally "no man" ] has gone before." English teachers find it ever harder to convey the subjunctive mood in a climate so casual that a Federal agency head tells a reporter: "It is not a 100 percent ideal situation. I wish it was." And the comma splice, a refusal to come to a full stop, is daily seen but not heard, even in advice to writers in Editor & Publisher: "Don't blame the reporter, blame the editor."

The triumph of informal speech shows in the increasingly conversational tone of newspapers. Contractions, which they once didn't permit in headlines, have become commonplace. Stories now routinely provide pronouncers like "Srebrenica (pronounced sreh-breh-NEET-sah)." More and more, print journalists look to the oral tradition of storytelling, and debate among themselves if it's permissible to adapt quotations so they sound, in print, more "natural."

The triumph of the spoken word also shows in the proliferation of obscenity. Americans probably don't talk any dirtier than they used to; it just seems that way. In writing, curses and dirty words have to be deliberate. In speech, they pop up naturally. The more voice, one might say, the more vice -- and the more vitality. The dominance of spoken English brings with it a healthy spontaneity. Language is as language does, and its vitality bubbles up in speech long before writers fix it in stone.

Misspelling is now a trivial offense, what with the increasing availability of computer spell-checkers; to decry them is as stuffy as objecting to the use of calculators for arithmetic. Today, the use of "like" wrongly does not connote ignorance or jeopardize a deal. Colloquial speech sells pizza. Sounds right? Feels good.

And yet there's a risk in unconditional surrender to the informality of spoken English. Everyone thinks out loud, impressionistically, but to base thought only on speech is to try nailing whispers to the wall. Writing, whether clear or clouded, freezes thought and offers it up for inspection. The triumph of oral forms and norms is welcome for its dynamism, but there's still plenty of reason to respect the rules. Language that sounds right can nonetheless steer us wrong. COOL CODE

WHY DO AMERICANS abbreviate so much? In a society organized from the A.A.A. for roadside emergencies to the Z.P.G. movement for Zero Population Growth, shorthand is an obvious reason. Another, not-so-obvious reason is coming into play -- insiderness.

People have always employed special languages, or codes, "for communication for intimates, with special names for one another, words that have private significance, deep looks, little sighs," writes the linguist Robin Lakoff in her book "Talking Power." Thus, anxious mothers have long whispered "F.H.B." -- family hold back -- lest there not be enough shrimp salad to serve all the guests. "O.T.T.," a theatergoer may say to his wife, to show he is grossed out by stage business he thinks is over the top.

But lately, this form of code has become more public and more pervasive. Magazines have sought to convey themselves as instruments of elite cliques by changing from names to initials. Women's Wear Daily spawned W in 1973. House and Garden, which published its final issue in July, was known as HG during its last six years. TNR is what insiders call The New Republic.

Fast-food restaurants also prize the insider cachet conferred by code. "Mickey D" is the name that boys in the 'hood gave McDonald's. "KFC" is the abbreviated nickname that Kentucky Fried Chicken finally adopted formally.

More recently, code abbreviations have appeared with increasing frequency in pop culture. Only squares need coaching to know that the name of the rap group N.W.A. stands for "Niggas With Attitude." The pre-teen-ager in the movie "Sleepless in Seattle" dismisses her boyfriend's father with an arcane "H and G," for "Hi and goodbye." "O.P.P., yeah, you know me," chants the rapper, leaving clueless listeners free to believe he means "other people's property," when sophisticates know he has a sexual reference in mind. T.F.S. -- thanks for sharing -- derives from the closing line of Narcotics Anonymous and other recovery-movement meetings. Now it's heard in casual, even sarcastic comment on, for instance, flatulence in the family station wagon.

The electronic conferences conducted on computer networks provide another fertile source of cool code. Participants seem to favor initials both for efficiency and hip snobbery. They might type "LOL," laughing out loud, or even "ROTF," rolling on the floor. For strong distaste, the abbreviation of choice might be "SMTOE," sets my teeth on edge. Or, to show withering contempt for a beginner, one might write "RTM" -- read the manual. Heated sentiment, cool code.