The secret is out. There is no mistake about it. Virginia is basketball country. For years, residents of the Commonwealth have been closet hoop freaks. But the frenzy of fans in places like Kentucky and L.A. has rarely graced Virginia basketball courts -- the result, many observers say, of bad teams and good breeding.

Well, move over, gang, because now it's Virginia's turn. And that's as definite as a Ralph Sampson slam-jam.

Sampson is, of course, the University of Virginia franchise. A 20-year-old sohpomore from Harrisonburg, Sampson is 7-foot-4 and the major reason Virginia has been No. 1 in the nation for much of this year. He is also the major reason that Virginia fans have exploded this year.

The explosion is no more evident than on game days in Charlottesville.

Oh, there is still evidence of the intellectual spirit so cherished by the university's founder, Thomas Jefferson: announcements of cello lessons, a philosophical discussion among the graceful buildings that Jefferson designed.

But there are also the Yah-Yahs. The Yah-Yahs are a group of students who come out for every game, and jump, scream and knock themselves out to cheer Virginia to victory.

The Yah-Yahs have their own special name for the Virginia team. The official name is the Cavaliers. But to insiders it's the Wahoos, and to the Yah Yahs, the 'Hoos.

"It's just a wilder name," explains one Yah-Yah.

Wilder name, wilder crowds, wilder times. "When I was in school," recalls one student from the early '70s, "we used to go the games just to boo the coach. His name was Bill Gibson, so we all called him Hoot. The team would start losing and we'd all start chanting, 'Boot the Hoot!'"

Gibson did get the boot, just after the 1974 season. He was replaced by the current coach, Terry Holland, who left Davidson College after five successful seasons.

When Holland came to Virginia, the university had had only four winning basketball teams in a quarter of a century. Two years after Holland's arrival, Virginia won the Atlantic Coast Conference tournament. In 1978, the team scored 20 victories and won a spot at the National Invitational Tournament. Last year, led by Sampson, Virginia stormed to national prominence with 24 victories and an NIT championship.

That championship started a 28-game winning streak that was broken only last Sunday in a 57-56 loss to Notre Dame, leaving Virginia 23-1 for the season. (This week, following the loss to Notre Dame, the AP and UPI polls dropped Virginia to No. 3 in the rankings).

"Even if they don't win any more, they're still the best as far as we're concerned," said a fan at the Clemson game several weeks ago, where a home-court, sell-out crowd sang and cheered its way out of University Hall. "Of course, they are going to win some more -- a lot more!"

Against Clemson, the Virginia crowd could barely be contained:

No more hoots on those few occasions when a Virginia player made a mistake. Instead, there were lots of, "That's okay," and moans of sympathy.

"Ain't no stoppin' us now" was the message on several T-shirts, while buttons that read, "See you in Philly (site of the NCAA finals)," were selling better than a Virginia baked ham.

An elderly woman, decked out in the orange-and-blue of the Wahoos, jumped to her feet at the first strains of the Virginia fight song and unfurled an orange-and-blue scarg emblazoned with "Cavaliers."

When Virginia cheerleaders, just ahead of the team, stormed onto the court with a shout of "yah-hoo!" University Hall started to vibrate.

"It gets wilder and wilder in here," says usher Bill Gilbert. "There are never any tickets available; you have to buy them way in advance. It would be impossible to sell them at the door. There wouldn't possibly be enough to go around."

The centerpiece of the wild times is Ralph Sampson, who last year set Virginia records for rebounds and block shots. Against Clemson, he was graceful and predictable awesome. In about a minute-and-a-half he dunked a shot, blocked a Clemson scoring attempt, passed to a teammate and followed a teammate's missed shot with another resounding dunk. The crowd was back on its feet, screaming for more.

But Virginia isn't a one-man team. Senior Jeff Lamp is eclipsing the school's all-time scoring record; Lee Raker, another senior, is a physical player with a fine outside shot, and underclassman Jeff Jones, Craig Robinson, Ricky Stokes and Othell Wilson are all quality performers. Like Sampson, Stokes and Wilson went to Virginia high schools.

Nor is Virginia the only school that is sparking the upsurge in basketball fever.

Old Dominion, in Norfolk, is the only college team to defeat third-ranked DePaul this season. And James Madison University, which is in Sampson's hometown, gave the Wahoos a scare earlier this season before losing to Virginia by one point.

The excitement of college fans is drifting down to high school teams, where players are finding more and more recruiters -- and opportunities -- as a result of the spotlight on the Wahoos.

"Sure, Virginia's success has created interested and is having a tremendous impact on the state," says Red Jenkins of Woodson High School, who has been a Northern Virginia coach for 22 years. "My own players show interest in (Virginia) because there are several hundred Woodson graduates in school down there. I'm sure that's the case at other schools as well."

The high school player most often mentioned as Virginia's best is David Hersey, a 6-foot-7 senior at South Lakes High School in Reston. Hersey has led South Lakes to a 17-1 regular season record.

Hersey signed with Richmond University before the start of the season in order to keep recruiting pressures from distracting him during his final high school season.

"David just felt that at Richmond he'd get plenty of playing time in the same type of position he's been playing for us," says South Lakes coach Doug Crupper.

The in-state schools are looking throughout the state for players like Hersey, and recruiters will be out in force at the Northern Region high school tournament next week, where Northern Virginia's top eight teams will be featured.

And this year, coaches say, the competition and the pressure will be intense for the region's best players, all trying to catch the eye of top recruiters.

No man knows that pressure better than Ralph Sampson, who was subject to what some observers say was the most intense college recruiting ever two years ago.

"When a kid's being recruited, he should get to know the (college) coach and watch the way the coach acts toward him," advises Sampson. "He should decide if he likes the players, the coach, the school, the campus and the location. He should find out the offensive and defensive scheme of the school and ask if he's going to get to play."

Then Sampson, the man most responsible for the basketball fever in Virginia and the man who last year turned down a half million dollar annual offer from the pros, says something designed to make Thomas Jefferson himself cheer:

"(High school players) should find out about attending classes and if the school has the classes they want. They shouldn't ask the coach that either, they should ask the teachers and their teammates. Classes are definitely important, because if you don't do that there's no sense in going to school at all."