Miranda Lambert was "all smiles" on Thursday night when she got to attend her first-ever Jimmy Buffet concert in St. Louis. But Lambert didn't just enjoy the show as a casual concertgoer; she actually joined Buffet onstage to help him sing his signature tune, "Margaritaville." Miranda shared an Instagram photo of her posing with Jimmy backstage while wearing a Hawaiian shirt and flower lei headband. Lambert said in the caption, "It was my first time to see him. I'm a #parrothead for life now!"