The country star also debuted a new song with Bailey Zimmerman called "Backup Plan," and later showed up as the Backstreet Boys' guest

Luke Combs threw a whole lot of exciting curveballs during his headlining Stagecoach set on Sunday (April 27), and one of them was an appearance from pop-punk rockers Good Charlotte. The band's Benji and Joel Madden hopped onstage with Combs to perform "The Anthem," a 2003 mega-hit off their first studio album.

Combs first brought out Zimmerman as they performed their collaboration, “Back Up Plan,” followed by surprise guests Good Charlotte. First, Benji and Joel Madden performed their hit “The Anthem” with Combs, then joined in on their “favorite” one of Combs’ hits, “Where the Wild Things Are.”