Demi Lovato was a couch guest on 'Late Night With Jimmy Fallon,' making the rounds to promote Season 3 of 'X Factor,' which marks her second round as a mentor on the show.

The 'Heart Attack' singer promoted her upcoming role on 'Glee' and also got in a few digs at the late night host over his, uh, vintage high school photos.

Lovato loves to busts people's stones, doesn't she?! She previously shared classic and embarrassing photos of her boss Simon Cowell on Twitter. There was no reason to think Fallon would be safe from her wrath.

Seated alongside fellow guest Michael Strahan, Lovato said she loved the former NFL'er and current daytime host from his soup commercials since he showed his gap tooth, which she also had. (And clearly had fixed!)

She said that new 'X' judges Paulina Rubio and Kelly Rowland have become like sisters to her.

Lovato of course had a little fun at Fallon's expense, and she had tweeted a "vintage" photo of the host and comedian and his Moe-from-The-Three-Stooges haircut before her appearance.

She spoke of her new guest role on "Glee,' saying she is stoked since she has known some of the cast members for a while. We bet her new castmates hope she doesn't get her well-manicured mitts on any high school photos of 'em.