WHAT DO you do about people who talk in the movies?

I don't mind the popcorn eaters so much, except when they reach the bottom of the bin and you can hear their fingers scrabbling. The sound of people chomping popcorn is rather peaceful and contented, like in the barn when the horses all have their nosebags on.

But the talkers . . . They seem to think they are in their living room watching the tube. Some of them even get up and go out every 10 minutes because TV has stunted their concentration.

Movie talkers have two things in common: They are physically unable to whisper, and they always sit behind you. But there are three distinct grades. Grade C is the easiest to deal with: You simply turn and glare, and they shut right up for at least a half hour. They are most likely inadvertent talkers, even as you and I, and usually they settle down after the credits anyway. Grade B talkers have to be told. Sometimes you have to tell them every 15 minutes because their attention span is not so good. The Grade A talker, luckily, is rare. He is the one who talks back.

And it is because of the A talker that most of us treat B talkers with care and finesse.

I mean, what you really want to do when someone chatters behind you is stand up, block his view of the screen, and snarl, "Will you shut up?" But you don't, because if he is an A type he will snap, "Oh fudge," or words to that effect. And remember, he is sitting behind you for the rest of the movie.

So what do you do? Go "sssshhhh?" (The Grade A will still say, "Oh applesauce.") This is only effective for a few minutes, and then you have to go "SSSSSHHHHH!" which makes you see specks in front of your eyes. It also leaves you feeling that you are coming over like the governess in "Sarah Crewe."

You could say, icily, "Would you mind?" but you have to watch out for the question form because it does, after all, invite a reply, if not a retort.

Some people go the rational route: "Please talk later," they say reasonably. Fine, if the talker is reasonable too. But as we know, reasonable people come to the movies to watch the movie, and therefore the movie talker is by definition someone who doesn't have all his switches on.

Sometimes the content of the talk calls for specific treatment. Once I got a guy who was really living the picture. "Oh my gosh!" he would tell his date, "they're going to crash!" And a minute later, "I think she's dead!" And then, "Will you look at that!"

I was going to turn on him and say, "I realize this is your first time at the movies. Nevertheless, do please try to contain yourself."

Of course I didn't. I shushed him, but he kept at it, entranced and oblivious. I got to like it after a while. It was quite charming.

In the end, there is only one infallible solution: the preemptive strike. It happened at a screening attended by a great film critic I know. Some guy had seen the picture before and wanted everyone to know it, so he loudly predicted the action, as in: "Now he shoots her, but she doesn't die." Things like that. If the movie had been "Citizen Kane" he probably would have called out, "It's his sled!"

Anyway, the guy refused to pipe down until at long last a large man clear across the theater slowly rose to his full 6 feet 4 and shouted in full stadium voice: "If you don't shut up . . . I'LL . . . KILL . . . YOU."

Try it sometime.