Martina McBride surprised a crowd of 30,000 Parrot Heads at Tinley Park in Chicago Thursday night (Aug. 26) when she joined Jimmy Buffett onstage. The two offered the first live performance of their current single, "Trip Around the Sun," from his License to Chill album. "I think it's great for her to come do this," Buffett told CMT News. McBride noted, "It's always interesting to sing on someone else's show and hear the reaction." Before the CMA's reigning female vocalist took to the stage, however, the fans saw one of their own singing background vocals with Buffett. Roylinn Harris, the winner of a CMT sweepstakes, backed the island guru on "Hey Good Lookin'." After her performance, Harris admitted, "Yes, I was scared. But after teaching school 30 years, you don't get scared much."