CLUB: The Last Outpost for Slam Dancers and Leapers : A Grand Slam : Nightclub: Red Square in Tijuana caters to rambunctious thrill-seekers who slam dance and leap to the sound of rock music.

First, Mario Fierro removed the metal trim from the perimeter of the tiny dance floor. Then, he covered the pillars inside his nightclub with padding.

“If I ever do another club, I would stick to the same line but do it more suitably, with rubber, like in the children’s playground at McDonald’s. You know? Nothing happens to you,” Fierro mused. Perched in his office loft, he had a full view of the slam dancers on the stage below--mostly military guys charging each other in a frenzy of bowed heads and raised elbows.

From the office window, Fierro is well positioned to take in Red Square’s other signature pastime: young men and women flinging themselves from the small metal balcony into waiting arms on the dance floor below--or through them, in the more unfortunate cases.

Almost all the thrill-seekers are from San Diego County, but Fierro’s club is in Tijuana--the region’s last outpost for slammers and leapers.

Some of them come because they are under 21, but most come to Fierro’s club, Red Square, and Iguana’s--which hosts live bands--because they can let loose and get away with some fierce acts generally censured by fears of liability north of the border.

But Fierro’s club is the only one to wholeheartedly embrace the stunts. Even at Iguana’s, in the Pueblo Amigo Shopping Center, slam dancers and balcony leapers are usually asked by the band to cool it, club-goers said.

While other clubs along the tourist-saturated Avenida Revolucion play a mix of rock, rap, hip-hop, and more, Red Square is only for rock purists--everything from the familiar echoes of The Doors and the screech of Metallica, to the hard-core sounds of Pearl Jam and Nirvana.

Many Red Square die-hards say the club scene in San Diego is just too cliquish . South of the border, in Mexico’s hard-core clubs for tourists, they can “be themselves.”

“There are only a couple of hard-core clubs in San Diego like this, and most of them are trendy,” said Renee Schwartz, 22, of Oceanside, a serious woman with dark hair and a nose ring, who was at Red Square on a recent Saturday for “the 30th time.”

“You come here as who you are. A lot of people put down this music, but you can just be yourself. You don’t have to dance like anybody else,” she said.

The celebration of individuality sometimes means brutal contact with other people’s body parts.

“It is that feeling you get when that rush comes up, and somebody hits you in the back, and you turn around and want to hit them back,” said 21-year-old Carlos Gonzalez, a towering Marine who got back from Japan four months before. “It’s a lot of fun. Everybody wants to hit everybody.”

Iguanas hosts live shows, everything from the well-known Special Beat to the underground Santa Barbara band Toad the Wet Sprocket. Club-goers have been known to climb onto the highest balconies to make their stage leaps, and, of course, slam dance.

But the activities are not exactly condoned, said Mike Garner, who works in promotions for radio station XTRA (91X) and often goes to Iguanas.

“Every time someone starts to slam, the band stops, recognizes that individual, puts a light on them, and says, ‘If you’re gonna keep doing that, why don’t you just leave?’ ” Garner said.

North of the border, club security guards have drawn the line.

“People just kept getting hurt,” Garner said of San Diego’s slam dancing days. “It caused more violence, more aggression. Clubs had to keep stepping up security, and security would just throw those people out.”

Enter the border zone, both criticized and lauded as a playground for reckless Americans. Fierro’s Red Square is capitalizing on that image: What appeals to customers, appeals to Fierro, who insists that his club has seen fewer fights and violence than other Tijuana nightspots.

“You get really pumped up. It is the physical contact,” said 23-year-old Jimmy Acosta after a frenzy on Fierro’s small dance floor. Acosta, a long-haired blond guy from Pacific Beach, looked a little out of place in the sea of military heads at Red Square. “Everybody is out there doing the same thing. It gets out of control, and you just flow with it,” he said.

While slam dancing is only triggered by a fierce beat, leaping from the Red Square balcony spans musical tastes.

On a recent Saturday, the colored strobe lights pulsated. Every now and then a plume of fake smoke rose up into the crowd, as an army of apron-clad waiters plied patrons with mostly German and American beer.

A young man dressed in black clutched the balcony railing and swayed back and forth to the voice of Jim Morrison--grinning. Then he was airborne, twisting onto his back and falling fast into waiting arms on the dance floor below.

Mostly smooth stunts. But not always.

“It was the rush ,” said Matthew, a 20-year-old sailor, remembering the epiphany that fractured his right foot one week earlier and left him in a cast, though still a loyal patron.

“I saw another guy do it, and everyone caught him. People caught me--but not enough,” he said, harboring no regrets. “There is no place in San Diego where I can come and do this. Slam dancing is such a unique way to express yourself.”

Fierro--a savvy businessman decked out in a jersey advertising French Vuarnet sunglasses whose daytime business is, ironically, insurance, built Red Square two years ago at the urging of a friend.

“We have fun, fun, fun. We sell happiness,” Fierro explained. “For me, this is the easiest crowd to control. I like to break up the fights as nicely as possible.”

As for the unusual dancing styles and semi-suicidal tendencies of his clientele, Fierro--who listens to everything from rock to Placido Domingo and traditional Mexican mariachi music at home--said he was startled at first, but soon conformed, trying to make his playground a little safer.

“I take precautions. But if we didn’t play this music, this crowd would leave,” Fierro said.

“In the beginning, I used to get scared, and I wouldn’t let them do it,” he said of the leaping, which even waiters and bartenders partake in from time to time. “We started out once with the music of Motley Crue. I ordered that record, but I didn’t know what it would do. . . . “I give them all the facilities, for when they get hurt, like a first aid kit,” Fierro said. “But now, for the past three or four months, we haven’t had any serious injuries at all.”

Despite theories that violent tendencies are acted out on the dance floor--not in real live confrontations--Fierro said patrons have, on occasion, smashed the bathroom mirrors and punched holes in the club’s walls.

“You work them too hard in America,” he joked, displaying a touch of gentleness and offhanded awe for the mysterious wildness that plays out inside his club’s walls. “They feel they are stars. That is why they are falling,” he said of his customers.

But pop sociology is just his sideline. Fierro’s main game is making money, and making sure the boys and girls come back--especially the girls.

On a recent visit, several young women tromped up the back stairs to his tiny office to pay him a visit. Nicole Fowler, 20, a club regular from Oceanside, said part of the club’s appeal is Fierro’s hospitality, and the sense of freedom his club bestows.

“It’s because they can,” Fowler said of the stage diving and general havoc. “Up in California, you can’t do that. But down here, if you can get away with it, of course you’ll do it.”

“People are looking for a getaway country. It is the closest choice,” said Fierro, who concedes that the entertainment caters to Americans--not locals--and doesn’t exactly evoke the subtleties of Mexican culture.

In fact, it is the Mexican hospitality, service and elastic rules that attract the Northerners, along with the conspicuous absence of local people.

“They play a harder kind of rock here and--I hate to say it--there are less Mexicans and more and more Americans,” said Matthew, the sailor with the fractured foot.

Local people who do choose to come in have picked up on those sentiments. Omar Lozano, 18, of Tijuana sat back with friends on a recent Saturday and checked out the general cacophony.

“It’s too much. Too hard,” Lozano, a college student, said of the music and excessive body contact. The fact that the club caters to Americans does cause some resentment among people like him, Lozano added.