ABERDEEN, MD., DEC. 12 -- Not far from the Army museum with the rifle that shoots around corners, and within earshot of test firings of 120mm tank guns, 222 Americans sat in a gymnasium here today and were told things such as:

It is an insult to let another person see the sole of your shoe.

The Saudi definition of sexually explicit is "uncovered torso between the knees and the neck and shoulder."

In Saudi Arabia, it is impolite to ask someone not to smoke, taboo to possess pictures of spouses in bathing suits, and not proper to keep your hands in your pockets when talking with Arabs.

"It's all rather strange and interesting. It's something new, that's for sure," said Ray Garcia, a machinist from Salt Lake City and one of an estimated 3,000 Americans registered at the Aberdeen Proving Ground, a massive military installation 25 miles north of Baltimore, for a two-hour crash course on the do's and don'ts in Saudi culture.

To lessen the potential for conflict between two very different societies, all U.S. military personnel deployed to the Persian Gulf are briefed on Saudi customs, Defense Department spokesmen said.

Almost all the students are ordinary people from across the country, librarians and data processors and engineers, whose Defense Department or military contracting jobs are taking them to the Middle East.

Three women from Chambersburg, Pa., found the Saudi restrictions on women of particular interest. After the class, they stood in a corner of the gym and talked among themselves.

Within 48 hours, they were scheduled to be in a land where women walk behind men.

"I heard that men and women have separate stores," said Barbara Osen, a 36-year-old computer operator. "You're supposed to have a man go in the store and get you what you need."

"I was told you can't eat in public," responded Carol Bishopp, 48, an accounting technician.

"That's right," said Osen. "If we go to fast-food restaurants, we're supposed to bring the food back to the barracks."

Amy Reasner, 20, the youngest of the Chambersburg crowd, kept repeating what she had heard: "The submissiveness. The clothing. The veils. Walking behind men. I'm too American for that."

U.S. troops generally have adhered to the many limitations imposed by the strict religious customs of Islam, but in dozens of interviews with troops in Saudi Arabia they said they have become weary of the ban on liquor, entertainment shows and religious Christmas displays that can be seen by Saudis.

But Joseph Smith, an electronic technician from Texarkana, Tex., on his way to the Middle East, said he believes some of the restrictions make sense.

"I think their tough laws repress crimes," he said, after hearing the stories of criminals being executed, stoned and mutilated. "I mean, as long as they have the right person and go through a fair trial, this could be good." He said he wasn't kidding.

The Saudi "customs and courtesies" course includes an introduction to Arabic expressions, such as Sabaah al-khayryaa, Mister Jones. ("Good morning, Mr. Jones") and Ureed azhab ma'ak ("I should like to accompany you.").

The audience, many of whom were middle-aged Americans who said they had never taken a language class, showed no facility with Arabic as they attempted to repeat the phrases. The slide show featured camels, a photograph of King Fahd bin Abdul Aziz and President Reagan, and maps pointing out Iraq.

Although many in the audience said they had heard bits and pieces of information about Saudi restrictions and customs, everyone interviewed said they learned something that was an eye-opener.

"I think I'm going to feel uncomfortable about the stuff about two men holding hands," said Grady Embrey, after learning that it was common for Saudi men to do so. Not staring at women or even looking in their eyes also could be difficult, Embrey said. Embrey, of Fort Rucker, Ala., will help to supply the 101st Airborne with repair parts.

He added that he believes the ban on alcohol "will work out for the better" for U.S. troops and personnel. "I've already heard that it has cut down on problems and accidents."