'Tween girls have been shrieking their appreciation for the 16-year-old pop star's hair for the last year or so, and now boys are (subtly) requesting the style in droves. Just as every girl wants hair like Blake Lively of "Gossip Girl," her brother wants to look like the artist who helped bring "Eenie Meenie" to the world.

"Boys are embarrassed" to ask for the cut by name, said Ms. Friedman, adding that 6 out of 10 of her boy customers ages 10 and older want it. "He's a teen heartthrob girls love; they don't want to be associated with that," she said.

Not all of them are so bashful. Five months ago, Tommy Ledger, a ninth grader in Vancouver, British Columbia, got a $175 chemical straightening treatment on his wavy auburn hair, telling fans of his YouTube channel that he was "going to have Justin Bieber hair."

"Girls always play with it in class," said Tommy, 14, in a telephone interview. "It's kind of frustrating sometimes. I'm trying to skateboard and they want to touch my hair."

It's hard to overestimate the popularity of Justin Bieber, whose fans in Australia grew so unruly last week that his concert in Sydney was canceled. A security clampdown in New Zealand ensued.

Most fans seem to agree that Mr. Bieber's skillful hair-flipping is part of his appeal. A video of him blow-drying his locks is all over YouTube, meant as a teaser for his new show on MTV, "The Diary of Justin Bieber." In it, he towel-dries his medium-brown hair then proceeds to have at it with a hair dryer, tossing his head with pubescent insouciance.

Also on YouTube? A 4-year-old boy wandering into his sister's room to ask if his hair looks like Justin Bieber's.

Call it the Flip and Switch, the Flow, or the Twitch: the Bieber hairstyle — with sideswept bangs that end about an inch past where the Beatles snipped theirs off — is everywhere. Tim Urban wore it on "American Idol" before he was voted off in late April, and Miles Heizer wears it on the NBC show "Parenthood" to play a brooding teenager. The idea is that the front-combed bangs are so long that they must be flicked aside constantly with a whole lot of attitude.

The majority of boys in the sixth-grade class of Ms. Friedman's son have the Bieber. "You can't see any eyes," she said, describing the scene at a school dance she chaperoned recently. "There are no eyes, and there's a lot of flipping."

Just last week, a boy who came to Cozy's Cuts surreptitiously showed his stylist a picture of Justin Bieber on his camera and asked her to replicate the look. "He said, 'That's what I want — don't tell my mom,' " said Ms. Friedman, whose three salons charge $29.95 for the cut.

Oscar Blandi, the high-end stylist, charges $100 to $150 for the Bieber, though other stylists in his Madison Avenue salon will do it for $75. He said that the last time he had seen teen boys so attached to a specific cut was in the mid-1990s, when Keanu Reeves wore his hair short and spiky in "Speed."

His take on the Bieber 'do? "It's really the old Linda Evangelista look, the gamine look," Mr. Blandi said. "The only difference is that he wears it pushed to the front."