On Saturday night, when traffic gets comfortably snarled and the sidewalks are jammed with halter tops and sailors on liberty, there are few spots on the Atlantic coast with more honky-tonk gusto than the Strip.

For two miles of taverns, discos and all-night coffee shops, the traffic on narrow Atlantic Avenue slows to a walk. Pickup routines and party invitations are delivered by the dozen. Boys in chrome-bright Camaros serenade girls on the sidewalk. And the radios, on a dozen different stations, compete with fiberglass mufflers as background sound.

Forget the pounding surf and saltwater taffy. On Saturday night, Virginia Beach is for cruising.

"It's like 'American Graffiti,' " says Rick Provo, a 31-year-old Virginia Beach policeman who patrols the most raucous, bar-crowded stretch of the Strip. "If you want police work, this is the place to come."

During most of the week, Virginia Beach is a vintage seaside resort, little different than Ocean City, Md. or Rehoboth, Del. A three-mile concrete boardwalk separates the surf and sand from beach high-rises and souvenir shops. Skeeball, bumper cars and candy apples are available at an ancient amusement arcade on one end of the boardwalk. And for one dollar, just 10 thin dimes, 78-year-old Mary Collins will admit you to the Serpentarium, where Snakes Alive sleep in the heat.

But Friday at sundown, the scene shifts to the Strip and families on vacation are lost in a younger, more freewheeling crowd. First the bars and cars are filled. Then police start filling up the jails. On an average summer weekend more than 40 arrests are made and 100 fines levied along the beach front for offenses ranging from fighting to public drinking to reciting lewd poetry on the hood of a moving car.

"If we were lenient, word would get around," explains Police Lt. William Haden of the Beach precinct. "We'd have people from everywhere coming in here to kick up their heels and terrorize our city."

Virginia Beach residents have long debated about how strictly the law should be enforced along the Strip. Merchants and property owners have a natural regard for law and commercial order. But they also realize that with $200 million in annual tourist revenues at stake, jailing large numbers of visitors is a bit like choking the golden goose.

"We don't want to become a honky-tonk beach, but we don't want to keep away the young people who come here, either," says J. Henry McCoy Jr., a dentist and part-time mayor of this 265-square-mile city, which depends on the relatively tiny beach-front area for a great part of its budget. "We're torn between the up-and-coming, fun-type tourist and the people who love to death the family beach."

Virginia Beach has never had a prudish reputation. Since 1880, when an elite beach-resort club was built on the sand where Blackbeard and his pirates used to sun, the Beach has grown like a frontier town.

"Virginia Beach was a real swinging place 30 years ago," says Lucille Doyle, a Beach merchant who danced to Kay Kaiser and the Dorsey Brothers at beach clubs now closed. "It had gambling, it had speak-easies . . . . I was 18, and my eyes were this wide."

Doyle and her husband Sonny run a combination newsstand, tobacco shop and Western Union office from a narrow storefront on the Strip. From their cash register, the Doyles watch the passing show and remember more elegant times.

"You very seldom see anybody walking along wearing a white suit," says Sonny Doyle as the nighttime traffic thickens outside. "Now they just ride and ride and ride. I don't understand it."

Officers assigned to patrol the Strip complain that the weekend beach crowd, high-spirited to begin with, gets unlawfully rowdy in the congestion of slow-rolling cars, bars and bodies. Tempers are more easily provoked and fists more likely to fly in a mob. Too often, say police, they are caught in the middle.

"Our officers are assaulted quite frequently," says police Capt. Ernest Buzzy, who heads the Beach precinct. During 1980, according to police records, 120 Virginia Beach officers were assaulted on duty. More than 60 officers were assaulted during the first seven months of this year.

Claiming reverse brutality, officers have called on judges to impose stiff, mandatory sentences on beach bullies who pick on them. That issue has been one of the two hot subjects in local papers here this summer. The other concerns a group of adolescent bike riders who have dubbed themselves "Surf Nazis." Police say they are children of middle-class Virginia Beach families who dress "punk" and terrorize pedestrians on the boardwalk.

One police officer this summer suffered a broken toe and a sprained ankle after crashing his motor scooter into a utility pole trying to avoid a bike rider he said was playing "chicken" with him by riding at him head-on.

Headlines about barroom brawls and self-styled Nazis do little for the blood pressure of local tourism officials. "Our stock and trade has been that we are a family resort area," says William Center, the director of the Beach Chamber of Commerce. Others in the city wonder whether the publicity is distorting the problems on the Strip.

"There isn't any more fighting going on today than there was when I started out as a patrolman 40 years ago," says Bill Halstead, a 59-year-old retired police major. "We had to manhandle people all the time."

Halstead owns the Peppermint Beach Club, one of the largest beer and dance halls on the Strip. On a Saturday night his patrons represent a cross section of the Strip crowd -- high school and college students, lawyers, laborers and a short-haired contingent representing some of the 89,000 soldiers stationed at five military bases in Virginia Beach.

The night crowd has a different perspective on the Strip. They say police are unreasonably strict and often rude.

"You can't go anywhere anymore and have a good time without being inside a bar or a house," says Vikki Walters, 18, a clerk at a beach motel. "It seems like there are cops every place."

"I was arrested for a noise violation one night because I was singing in my car," says Cheryl Courson, a 20-year-old beach waitress from Pittsburgh. "I said, 'I know I'm not Diana Ross, but don't make me pay for singing.' "

Police officers such as Provo and his 28-year-old partner Jim Walters say the job is too demanding and the crowd too unfriendly for them to act like Starsky and Hutch. Show a smile and some drunk will see a target, they say.

"I worked in an inner-city precinct in Petersburg for two years, in lower-class neighborhoods, and never got assaulted," says Walters. "Then I come to Virginia Beach, where it's mostly upper class and what happens? I get the s--- beat out of me three times."

While Provo and Walters walk up the Strip to begin another night patrol, a caravan of cars, jeeps and custom-painted vans rolls in the opposite direction, looking for action.

"It's so easy to pick up women in Virginia Beach," says Ken Huddle, a 26-year-old sometime car salesman from Bethesda, shirtlessly piloting his ocean-green Bronco jeep on a slow roll through an all-night party. "All you got to do is ride up and down this strip and you can't miss. Ocean City doesn't have anything like this."

Riding shotgun in Huddle's Bronco, Tom McCay, 24, has just launched himself half out of the jeep after spotting another car full of possibly beautiful blonds.

"I have a feeling," says McCay, his eyes merry with abandonment, "we're going to all end up in jail."