The spur-of-the-moment performance took place on Tybee Island, Georgia, where Cyrus is shooting a new movie – The Last Song – scheduled for a 2010 release.

Cyrus had just finished gobbling up a plate of snow crab legs at StingRay’s Restaurant when she asked a local music duo if she could sit in. The 16-year-old star grabbed a guitar, stepped up to the mic and sang the Tim McGraw / Faith Hill duet “It’s Your Love,” before launching into a new song of her own.

Word quickly spread among kids (and parents) that something was up.

“By the time she finished the first song, there must have been 50 little girls and their moms who came rushing up,” said StingRay’s owner Ray Rogers.

After two songs it was gone, leaving only a memory, and a new collection of videos on YouTube capturing the moment.

“She played those and then we got her out of here,” Rogers said. “We asked her, ‘What do you wanna do?’ and she said ‘I want to get out of here.’ So we walked her to a side entrance nobody knew about and got her in her car.”