Flashback: Demi Lovato, Jimmy Fallon Sing Metal Cover of 'Barney' Theme

Then-Disney star Demi Lovato showed off a surprising side of her music taste during a 2008 appearance on Late Night With Jimmy Fallon: her love for metal. Joined by Fallon, Lovato channeled that love into a raucous headbanging version of the theme song for Barney, the show where she got her start in the entertainment…