Friday nights the Mount Vernon District Park & Ice Rink in Fairfax County fills with children too old to hang around the house at night and too young to drive away.

Twilight brings nearly 100 scions of suburbia to the frozen expanse under a cavernous roof. They spill out of their parents' station wagons, trailing sweet perfumes and chewing tobacco. Anxious, exhilarated, they take over the ice, gliding and wobbling away from childhood.

"It's always funner," says 13-year-old Jeff Oehrlein, "to be where the parents aren't."

Jeff and his friend Frank Althouse, also 13, lace up their hockey skates and consider the evening's possibilities at the county-owned center. Will they meet girls? What should they get from the snack bar? Is it too early to play a video game?

"Go for it!" says Jeff Taylor, 13, shoving his elbow into the side of his friend, Jack Murray, 13.

"It means go out there and meet a girl," Jack explains. It is not an easy thing to do, and Jack has given the matter some thought, as have the others. "You can bump into 'em and you get to know 'em," he says. "Or you can fall down in front of them. Or maybe if you have a friend who knows a lot of girls . . . . "

"I usually don't use a middleman," says Jeff Oehrlein. "It makes you look like a fool."

"Sometimes, though, you show off and do spins, and her friend will come up and tell you that she likes you," says Jeff Taylor.

"Yeah," says Jack. "Then we try to get them to go outside."

Most nights girls outnumber boys two to one, and the boys don't mind. "Girls? Yeah," says Lee Johnston, 14. "That's why we come here. That's the major reason." For their part the girls pretend to look right through most of the ardent acrobatics, but the lavatory resounds with proof to the contrary: "Trish, that guy is not Chuck, he's Doug!"

The lords of the rink are the 14- and 15-year-olds. Jeff Kranz and John Kaiser, Doug Scott, John Carlson, Lee Johnston and Tom Stone have been meeting at the rink Friday nights for so long they don't even bother to call each other to see who's coming. "We're always here," says John Kaiser.

Cutting a dashing figure is thought to be difficult while wearing the rink's blue plastic rental skates. So most Friday night regulars have their own skates. For the boys, figure skates are a social disgrace. One of the most hilarious events this season was the time Lee forgot his skates and had to skate in rental figure skates.

"It was so excellent," says Jeff Kranz, as his friends dissolve into fits of giggles at the thought. "Figure skates! I'm serious."

On the ice, the gang skates in a loose pack, and soon the boys begin to peel off their sweatshirts and jackets. Steam rises off flushed arms and faces. John Kaiser races around the rink and is sidelined by the rink guard for excessive speed. The penalty: 10 minutes off the ice. There's only one thing to do. He heads for the video games, solace of the frustrated skater, source of welcome revenues for the county rink.

Frank is already pumping quarters into the green Jungle King machine. "I play these when I get frustrated skating," he says. "But this dumb game is just as bad." The rink earns $600 a week from Jungle King alone. Frank will spend $4 tonight. Other skaters are waiting behind him, in the silence that video etiquette demands.

Friday night's frenzy is fueled by a 19-year-old part-time deejay named Jeff Kahlick, who works behind the snack bar when he's not in the sound booth. It is Kahlick who controls the button that spins the disco ball, a mirrored sphere the county hangs from the rink rafters. Disco may be dead, but the Friday night crowd hasn't heard the news. When the lights go down, the ball sends amber sparks around the arena and the pace on the ice picks up.

But not for the less expert. Amjad Fusaisy, 13, and his friend Paul Izzett, 10, are wincing off the rink. They walk to the snack bar, where Paul orders a jelly toast sandwich to the vocal disbelief of older children nibbling French fries. "You should try it," Paul suggests calmly.

"I usually burn on the ice," says Amjad, fingering his rented skates. "My skates are too tight or too something. He doesn't know how to skate, he just runs."

"Well," responds Paul, swallowing his toast. "At least I don't fall down."

By 9:30, parents have begun to take their children back. Jeff Kranz, John Kaiser, Doug Scott, John Carlson, Lee Johnston and Tom Stone assess the evening: The $15 they have spent on food and video battles has not brought total happiness.

"Not too good," says John Carlson.

"I've seen better," agrees Doug.

No girls.

"Yeah," sighs John. "You got it."