The funny thing about the jokes that amuse a high school basketball team is that nobody seems to know where they come from. One player says something silly, then another, then another, and before long the undefeated Madison Warhawks are rallying around a rodent.

“This is weird, and I don’t know why they do it,” Coach Kirsten Stone begins, “but they call themselves the ‘rats.’ ”

A journalistic mission to find the origin of this nickname was unsuccessful. Stone said she had no idea. The Makrigiorgos sisters, giggling, say they always have endearingly called each other rats; as for why, senior Tedi shouts, “I don’t know!”

“Everybody used to think it was childish,” she said, “and then they accepted it. So now everyone’s a rat.”

“Everyone just channeled their inner rat,” sister Amalia Makrigiorgos added. Then the Warhawks found out that on the Chinese calendar this is the Year of the Rat, which just about sent this giddy team over the edge.

With Madison 22-0 heading into the playoffs, it’s hard to argue with the calendar.

Such is the vibe of a juggernaut that is striking just the right balance: goofy but mature, cognizant of the pressure but not consumed by it. Twelve players, six sisters (four twins) and a coach who’s pushing all the right buttons: That’s what it took to produce a rare perfect regular season in Virginia Class 6 basketball, by a team that welcomed its winning streak instead of buckling underneath it.

“It’s not an overwhelming pressure,” sophomore Grace Arnolie said, “but it’s there, and we can see it there. It’s in our record. We know that we’re capable of [going undefeated], so we need to continue being capable of that.”

‘You will get made fun of’

Seasons such as this one don’t come often. Madison, which begins play in the Concorde District tournament next week, is seeking a 30-0 season if it continues winning all the way through the state tournament. Only one team in the history of Virginia girls’ basketball has outdone that: Oakton in 2011-12, at 31-0.

At the state’s highest level, such a winning streak demands consistency almost unheard of in high school basketball. This year’s Madison team won twice against Georgetown Visitation, winner of 13 straight Independent School League titles. Eighteen of the other 20 wins came against Class 6 opponents, the exceptions being Nazareth (N.Y.) and No. 7 C.H. Flowers (16-1).

“There’s so much that goes on in the kids’ lives now, way more that ever went on in my life,” longtime Oakton coach Fred Priester said. “It’s just been exponential, and so there’s so many things that can derail it. … I think they have a good chemistry going.”

Priester knows a little something about controlling undefeated seasons, having guided his team through a spotless record eight years ago. Oakton has played Madison twice this year, and Madison won those games by a combined 25 points.

Madison has navigated this success by keeping things breezy in practice. When a player slips and falls on her knees or overruns a fast-break layup by so much that she fires it into the underside of the backboard, the rats are going to laugh.

“You’re not safe at practice,” Tedi Makrigiorgos said. “You will get made fun of.” For what? “Everything.”

Stone, the 12th-year coach, said the consistent joking “lightens the tension. They make fun of me. I make fun of them. It’s kind of a stress reliever.”

Last season, Stone kept five freshmen on varsity: Grace and Alayna Arnolie (fraternal twins); Katie and Jill Koshuta (identical twins); and post player Kiera Kohler.

When Madison started practice with a handful of 14- and 15-year-olds, Stone noticed that they were always laughing.

“At first I used to get mad,” Stone said. “And then I watched them all. If you have fun at practice, it makes everything easier. They work hard, and they can laugh.”

Knocking on wood

As the team’s winning streak inched forward, Madison’s games became community outings. Stone, who played at Madison, said, “Vienna is a small town, and it’s the only one around, I think, that’s still community-based.” Gradually, people started to hear about the best show in town.

Fans of all ages pack the gym for the Warhawks’ mesmerizing brand of basketball. Their games are infused with so much joy. Little girls come and visit after the games. Fans want pictures afterward at Tequila Grande. One woman left Stone a two-minute voice mail commending the kind of team she put together: “Your girls are so nice.” Stone played it for her players.

The Warhawks appear to be favorites to hoist a big trophy in Richmond next month, but they don’t simply assume they will make states. They say they’re not superstitious, but they take preventive measures, just in case.

“I’m knocking on wood as I say this — [people say], ‘Oh, states, you’re going to states, right?’ ” Alayna Arnolie said. “And I’m like, ‘Do not talk about that.’ ”

Coaches spend years searching for the equilibrium Madison has found. Stone didn’t have to. She stumbled upon a dozen girls who have that indefinable quality that makes seasons special. Perhaps because half of them have a sister on the team, they stay together and move as one more than any other team.

“There’s no way to control the fun that we have,” Tedi Makrigiorgos said.

There may be no way to stop it, either.