Exclusive: Backstage With The Jonas Brothers!

Boys no more, The Jonas Brothers have been heating up concert venues around the world with their summer tour (sponsored by Huawei) and only ET was invited behind the scenes of their very last concert of the season where the guys let us in on the "real story" behind Nick's unexpected, yet welcome introduction into the world of sexy internet selfies.

Pics: Hollywood's Sexiest Shirtless Men!

"He actually didn't even want to post it," revealed Kevin of the buff, shirtless pic posted to Nick's Instagram page in July (click here for a refresher). "The real story is he was like, 'No, no, no,' and we all were kind of like, 'You've gotta post the picture!'."

The response from the internet was enormous, but an amused Nick told ET that although "it was fun to see the reaction" he was moreso happy that other diabetics were encouraged to get healthy.

And if fans we're jolted by characteristically shy brother's sexy reveal, they may need to hold onto their hats in regards to what's to come. The 20-year-old performer's new flick, Careful What You Wish For, apparently will give viewers even more of an eyeful on the big screen.

"I'm shirtless in this movie quite a bit…pantless too," said Nick. "No clothes."

Though admittedly a nerve-wracking experience, the young Jonas said wouldn't have done it if he wasn't fully invested in the project.

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"The director was great and my co-star was great and the scenes are a part of the story," he explained. "The sex scenes in the movie are important for the storytelling and I think it's a really intense movie that I think will capture a lot of people's attention."

Click the video to hear more from the brothers as they reflect on the end of their summer tour at the Gibson Amphitheater in Los Angeles, plus dish on their upcoming album V, due out this fall.