It’s a tawdry showbiz ritual: The ingenue, angling to lose the child-star image, decides to relaunch herself as a serious grown-up artist. . . by stripping to her undies for a sexy photo shoot.

It’s trite, and it’s a little sad. But at least it’s not a sexist tradition anymore! Because now the boys — ahem, men — are baring the flesh, too.

Nick Jonas made waves last week for his “shocking” (NSFW) photos gracing the latest issue of Flaunt magazine. The former teen-idol lead singer of the Jonas Brothers family band, now 22, seems to have traded his old squeaky-clean image (he dated Miley Cyrus when she was still Hannah Montana) for a pair of boxer briefs and an ab roller. The hand that once wore a purity ring is now seductively pulling down his jeans as the other caresses his own precariously clothed bottom. With both a new TV series (“Kingdom”) and an upcoming solo album to promote, he’s deploying toned pecs, a happy trail and a saucy crotch grab in the Marky Mark-inspired photo shoot.

From left, Joe, Nick and Kevin Jonas in simpler — and more innocent — days. (Dan Hallman/Invision/AP)

Hey, it worked for Zac Efron. The Disney Channel phenom, launched to fame with “High School Musical,” made a point of hiking up his shirt to show off well-groomed abs on a 2007 Rolling Stone cover — forcing his proudly post-pubescent body into the spotlight, as if to literally prove he’s an adult. Maybe it’s a coincidence, but it got him out of the rut of teen roles and into some grown-and-sexy romantic leads, not to mention an edgy indie flick where an Academy Award-winning actress peed on him.

Daniel Radcliffe, while still stuck behind the boyish spectacles in the wildly popular “Harry Potter” series, took to London’s West End in 2007 to perform in the play “Equus” — which called for onstage nudity and simulated sex. “He’s proved he’s not Harry Potter, he’s Daniel Radcliffe,” his director Thea Sharrock said when the production moved to New York. Mission accomplished!

The Internet collectively lost its mind when promotional photos for “Equus” showed a half-clothed Daniel Radcliffe caressing a horse. (Peter Thompson Associates, Uli Weber/AP)

But going overtly sexual hasn’t always worked for the young women: Witness Jessica Biel, who nearly got kicked off of the family show “Seventh Heaven” after posing topless for Gear magazine when she was only 17; or Hilary Duff, whose post-“Lizzie McGuire” career never really took off despite (or because of?) saucy photos in Maxim. And the track record seems spotty for the fellows, too. After the first “Twilight” film, young Taylor Lautner lost his shirt, grew some muscles and gained a serious fan-girl following — but by getting typecast as hardbodied eye candy in every subsequent film, he hasn’t put himself much closer to an Oscar.

Justin Bieber hasn’t quite found a look that works for him. The oversized hoodie, sideswept bangs and baseball cap were perfect for a 15-year-old boy crooning to a captivated audience of 12-year-old girls. But ever since a major image-shedding haircut at 16 and the release of the bass-thumping and sexy music video-strutting “Boyfriend” at 18, you’d be hard-pressed to find a picture of the Biebs wearing a shirt (or a modicum of dignity.) His music matured — and his criminal record grew — but all of that was wrapped up in a tight bow of inked biceps and a wisp of facial hair.

Obviously, the thinking seems to be: If fans and audiences see stars as mature, so will studio executives and record producers. It’s hard to think of a female teen star other than Taylor Swift who has made the leap without revamping her image. So now that the guys are getting in on the act? Well, it isn’t the gender equity we’ve been searching for in the entertainment industry, but eh, it’s a start.