WE ARE all going to learn today to be terribly American. If there is one thing that Miss Manners abhors--and, good-natured as she is, there are about 127, and twice as many on humid days--it is the idea that European manners are superior to American.

One seldom finds an American so shameless as to state that belief outright. But Miss Manners knows that this sort of self-denigrating snobbery is what is behind, for example, the claim that the Continental style of using the knife in the right hand and the fork in the left, to eat as well as to cut food, is superior to the American style, which is to switch the fork to the right hand in order to convey the cut food to the eager mouth.

"It makes more sense!" claim those who favor the European method over the American. "It's much more efficient."

Well, the day that etiquette has to make sense in order to justify the presence of customs and courtesies in daily life will be the day Miss Manners gets herself a job selling cookies door to door. And as for efficiency--ask your doctor if he doesn't think you are getting your food to your mouth quite efficiently enough as it is, and whether you might perhaps benefit from an additional two-second pause between bites.

The fact is that the founders of America, while not insensible to the appeal of graceful society (Miss Manners refers you to some of the racier biographies of dear Thomas Jefferson and Benjamin Franklin) believed, as does Miss Manners, that good manners can be modified from the basic royal court model, which assumes hereditary class differences, to a democratic one where honors are modestly apportioned, and only to individuals.

Thus we do not bend our knees to our highest officials (much less to foreign ones, such as visiting royalty), and we address the top one as mere "mister" with his job title: "Mr. President." There are no titles for members of his family, and his wife is properly addressed as "Mrs. Reagan" only. "First Lady," although sometimes useful as an identification, always seemed to Miss Manners to be rather a silly title, although she has been fond of seeing, in various administrations, an occasional reference to a White House pet as the First Dog.

All this, however, is not really what has Miss Manners worked up on the Fourth of July, when she ought to be resting up for the fireworks and lemonade. She is leading up to a plea for a return to a particular 18th- and 19th-century American tradition, with impeccably philosophical as well as practical justification.

Until the beginning of this century, when so many things have gone wrong (oh dear, that's just the heat again), the custom of tipping was considered highly un-American. To accept a bit of money as an optional handout from the beneficiary of one's honest labor was recognized as the quintessential example of Old World servility, unsuitable to a free and dignified people for whom honest work, of whatever kind, involved regular compensation.

Whatever happened to that, folks? Perhaps the anxious people who confide to Miss Manners their worries about correct percentages, the labor force dependent on whimsical generosity, and, most important of all, the employers who believe that an opportunity to collect tips is a substitute for wages, could get together and work out a sensible system for full compensation to people who provide needed services.

It would be a lovely Fourth of July present for Miss Manners, not to mention the nation. MISS MANNERS RESPONDS

Q. I am dating a wonderful guy in the military service. My difficulty is that quite often, when I am with his friends, they talk only about military subjects I know very little about, and, worse, they use slang I don't understand. I feel ridiculous stopping them every few minutes to ask, "What does that mean?" and my date and I cannot get them to change the subject for any length of time. I feel silly sitting at dinner and never saying anything. Do you have any suggestions on how I can be a more active participant, short of bellowing, "Shut up and talk about something I know?"

A. Having been brought up in an era when young ladies were advised "to learn about sports so you can talk intelligently to boys about their interests," Miss Manners is loath to perpetuate such depressing advice.

However, when either ladies or gentlemen choose to pair themselves up with people with whose occupations or preoccupations they are not familiar in detail, they have to face the problems of friends who insist on talking shop. There are only two ways to deal with this, and bellowing "shut up," or whatever modified form of this you have used in your futile attempts, isn't one of them.

You may separate yourself from that part of the person's social life. This is not attractive to courting couples, although married ones learn to appreciate the value of saying, "Look, if those people are going to talk stock market (or wines or politics) all night, I'm going to the movies."

Or you may learn enough to engage in some modest participation. Get some basic training. You might ask your friend to put together a glossary of slang terms--and his friends might have fun helping him with it, which would draw attention back to your problem.

Q. Recently, I was at the post office where, upon my entering, there were two customer lines open. Two people were waiting in line one, and at line two, only one person was being waited upon. I decided to stand in line two, completing a foursome: Two people waiting in each line. After waiting approximately five minutes, the person in front of me finished his transaction and left. During the preceding time, I had been debating whether to let the second person waiting in line one go ahead of me, since she had entered before me.

I didn't have to debate for long, since the lady (I happen to be a lady also) left her line and strode right in front of me to take what would have been my place. I kept silent.

My questions are: Should one offer her place in a situation of this kind? If the woman in question and I had both waited 20 minutes or longer, as compared to waiting 30 seconds after my initial entrance, would that make a difference in relinquishing my place? When another person in a line forces herself in front of you, how do you respond?

A. Miss Manners (who happens to be a lady also) tends not to start fights in post offices. If one transaction, ahead of her, took 20 minutes, however, she might.

The basic rule is that one chooses a line and sticks with it; like traffic lanes, it is a matter of luck as to which will move and which not. Miss Manners finds drivers who refuse to stick with their choices a nuisance, but in any case, weaving by breaking in is not permitted on foot. Therefore, it is a great courtesy to permit such a person to step into one's own line, and an equal rudeness for someone to do so without being invited.

Q. This summer, our daughter is to be married in an outdoor ceremony. If we provide chairs for all of the guests, most of the grassy area will be covered with chairs. In order that people move around after the ceremony (the reception is in the same spot), a good number of chairs will have to be removed and placed somewhere.

The alternative is to provide chairs for part, but not all, of the guests, as some people would stand or sit on the grass during the ceremony. If we did this, how do we assure that the seats are reserved for the older guests who really need them? So, my question to you: To seat or not to seat, or who gets the chairs--the fleet or slow of foot?

A. The picture arises, in Miss Manners' mind, of a bunch of surly young people--the bridegroom's step-brother, the bride's sorority sisters, the girl the bridgroom's parents think he should have married--sprawling on the chairs, while a knot of elderly people--grandmothers in matching lace and hats, rich uncles without direct heirs--stand about uncomfortably, tips of their canes sinking into the lawn.

Miss Manners does not like this picture, and prefers to assume that it could never take the shape of reality. She therefore thinks that a few chairs would be enough. As a precaution, though, she would put a satin ribbon across them to make them looked reserved, and instruct the ushers to approach appropriate people with the question (not an absolute direction) of whether they would prefer to sit during the ceremony.

Feeling incorrect? Address your etiquette questions (in black or blue-black ink on white writing paper) to Miss Manners, in care of this newspaper.