I learned something recently that has taken the crush out of Christmas crowds and the mash out of Metro.

What happened was I went to a Bullets game at Capital Centre and got bumped, pushed, shoved, tripped, stepped on, elbowed, cut off, jostled, blindsided and all but blown away while trying to make my way from car to beerseller to seat to bathroom and back again. Basketball fans are bigger-and-stronger-than-standard people, and it isn't hard to figure out why, but they are not normally meaner or ruder than any more random collection. I'd never been roughed up like that before. I decided it must have been because it was a Knicks game and had drawn a lot of New Yorkers. We all know about New Yorkers.

Then I was similarly manhandled (and woman handled) at National Theater. The ultimate indignity came when a little old lady who stood nose-high to my navel body-blocked me so hard I dropped my egregiously overpriced orange drink.

Obviously somethiing basic had changed and there was an underlying principle. I began to understand it after I remembered the sad saga of Sadie the Boss Hen. Sadie had been numero uno in the pecking order of our family chicken flock of ancient days until the time the end of her beak got broken off when she got it caught in the lid of the mash trough.

Over the ensuing weeks, hanicapped by her blunt business end, she lost some of her weight, many of her feathers and all of her authority. But Sadie didn't understand that the rules had changed. She would come breasting up to the trough as always, expecting the lesser ladies to give way, and wap wap wap they would blast her in the head until she lostd what little wits she had. Suddenly every hen in the flock was her social superior, and they got even with a vengeance. At length her wounds became infected and she died.

Something like that was happening to me. I had recently reformed after a couple of decades of carrying more than 200 pounds on a less than six-foot frame. My waist reduction yielded all the benefits the health nuts had promised, plus a bonus: an understanding of crowds and how to avoid being trampled by them. Each of us has a certain place in the human pecking order. It has to do with size (mainly), age, beauty or lack of it, personality, dress, and possession in greater or lesser degree of that quality known as presence.

As strangers move among one another they perform an intricate ballet. One goes ahead and another yields according to the interplay of those factors; most of the adjustments are made unconsciously and with amazing rapidity. The process is often so subtle as to be sublimal, and it is far from perfect. Collisions come at blind corners and stalemates occassionally occur when closely matched strangers meet. The women's movement has screwed up door-handling to a fare-thee-well, because one female person will smile at you if you hold it for her, while the next will hiss.

What I was doing was driving a medium-man body yet still sending out big-man signals. When I was fat, 9 of 10 people would yield to me, but my new place on the scale was a 7 or perhaps a low 8.

I still am studying my new status and occasionally make serious errors, but I have learned some general rules about crowds. Careful application of them can win you a promotion to several grades above your rightful rank, which may get you home in time to cheat the babysitter out of two or three dollars.

Dress spectacularly , whether well or badly. A Bill Blass turnout or a really filthy army field jacket will give you an equal edge in that critical first moment of encounter, when most of these confrontations are decided.

Carry something , whether it's a drink, an umbrella or a cane. Held in front of you, it extends your Cone of Command. The best object to carry is a small child; everybody yields to a babe in arms. But this is not often convenient.

Use your blockers . If a more commanding (a bigger, say, or more beautiful) person is going your way, fall in behind. Keep as close as you can, both to keep the other person moving and to keep others from copying you. The technique is known as drafting in stock-car racing.

Read the terrain. Don't follow blindly, but look for shortcuts. People tend to move like cattle (they even moo in the RFK pedestrain tunnels), so be ready to sideslip or take shortcuts as openings develop. To get off Metro near the escalator, get on Metro near the escalator. Work the edges of a constricted stream of people; unlike liquids flowing through a tube, crowds tend to clot near the center.

Be decisive . Take opening immediately. Always move in high gear when possible. A fast-moving 7 can outrank a 9.

Avoid discussions. Don't chat with those you're temporarily stuck near, you'll find yourself adopting their pace. As Kipling said, "He travels the fastest who travels alone." Answer all salutations such as, "Hey, Buddy," with mumbles and keep moving.

Avoid eye contact . Unless you are a natural 9 or 10, most of the strangers you encounter will outrank you, and if you meet their eyes the game is up. Pretend you don't see the monster lumbering across your bow and he'll probably yield.

Miscalculations can be costly. None of the rules apply in burning theaters or New York City. All New Yorkers are 11s, and you could get killed.