The Veronicas reveal the untold story of their unreleased Suite Life of Zack & Cody song

Remember when the Veronicas stole Zack (Dylan Sprouse) and Cody's (Cole Sprouse) jobs on The Suite Life of Zack & Cody?

Back in 2007, identical twin pop duo Jess and Lisa Origliasso guest starred on the two-part "The Suite Life Goes Hollywood" special as undiscovered singers who end up replacing the boys as the stars of the TV show based on their lives thanks to an impromptu performance of "Cry." But that song has never actually been released — and 15 years later, the singers are finally revealing why they chose to perform that track instead of their hits "Untouched" or "4ever."

When EW caught up with the Veronicas backstage at When We Were Young music festival in Las Vegas on Saturday, the Australian pop stars looked back on what it was like filming their Disney Channel debut. "We still get tagged [about] that," Lisa says. "I guess they're still playing it."

"Yeah, they play it all the time," Jess adds. "We were babies in that. Our managers were just like, 'Go along to this filming thing.' We didn't know what we were doing."

The sisters laugh as they admit that they hadn't even heard of the show before agreeing to guest star on it because they didn't have the Disney Channel in Australia. They loved meeting the Sprouse twins and had fun while on set, but they faced a major problem when figuring out what song they would sing in the episode.

"They didn't have clearing rights for any of the songs on our albums," Jess reveals. "They were like, 'You just have to play something else you've written,' so we ended up playing a song that's not on any of our albums called 'Cry' that we wrote when we were 16, because we couldn't think of what to play. It was the only song that wasn't on our publishing company [and remains] unpublished."

The Veronicas experienced another major pop culture moment one year earlier when their song "4Ever" was featured in the movie She's the Man, starring Amanda Bynes and Channing Tatum. "I watched it again recently," Jess says. "That was so wild when that happened."

But if the sisters could pick a current TV show or movie to feature their music, they'd love to see it used in a Tim Burton project. "I think 'Untouched' in a Tim Burton film or the Wednesday show or something while she's playing the [cello] would be sick," Jess says.

"That's a brilliant idea," Lisa says. "We need to pitch that to someone."

—Additional reporting by Jess Leon

Sign up for Entertainment Weekly's free daily newsletter to get breaking TV news, exclusive first looks, recaps, reviews, interviews with your favorite stars, and more.

Related content:

• From Frozen to 'Iron Man,' all the best covers performed at When We Were Young music festival
• The secret life of the Veronicas
• The Veronicas discuss new album In My Blood
• The emotional highs, lows, and everything in between from When We Were Young music festival