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.