On an appearance on The Ellen Show, the host inquired about the song’s subject. “There’s supposedly a song about Nick Jonas,” Ellen stated to Demi, to which the singer said, “Ya know, something that I will always keep to myself is who I write my songs about.”

On Sunday, Demi Lovato joined the Jonas Brothers on stage in New Jersey for the opening night of the JONAS20 tour, dazzling in statement-making rhinestone-covered jeans. For the “Camp Rock” reunion, Lovato, 32, slipped into a pair of slouchy crystal-adorned Acne Studios jeans ($1,400).

The band — consisting of brothers Joe, Nick and Kevin Jonas — kicked off their 20th anniversary tour on Sunday at MetLife Stadium in their home state of New Jersey. But to make it more special, they surprised their fans with some special guests throughout the show, including Demi Lovato .