According to Taylor Swift, singer Andy Grammer was merely passing through town, so she invited him to perform onstage with her in Nashville this weekend! What a way for Grammer to pass the time, huh? By performing onstage with one of the biggest music superstars out there? Some guys have all the luck, don't they?

Swift introduced Grammer to her fans and gushed about how much she loved the song, admitting that when she's having a bad day, she listens to Grammer's 'Keep Your Head Up.' That ringing endorsement from a megastar should send his iTunes single sales through the roof.

The pair performed the song, with Swift gyrating and dancing more suggestively than we are used to seeing her do as she sang with Grammer. In her sparkly black mini dress, she and Grammer (sporting a black leather jacket, grey jeans and sneakers) had onstage vocal chemistry. The crowd was certainly feeling it, too.

Swift clearly loves this song, because she was singing along and dancing the entire time. Seriously, there was a crackling energy during this performance.

One thing we've learned about the lovely Swift during her 'Speak Now' tour is that she is a complete and total music geek. From those lyrics scrawled on her arms via a Sharpie to all those regional cover songs to all those onstage guest stars, she is an unabashed music nerd, just like us!

Swift and Grammer ended their duet with a big hug. Maybe they've sowed the seeds of a future recorded duet? Only time will tell.

Watch Taylor Swift and Andy Grammer Perform 'Keep Your Head Up'