Taylor Swift just surprised lucky fans in Nashville ... taking the stage at Travis Kelce's Tight Ends & Friends charity concert to sing "Shake It Off"!
You can feel the energy at Music City's Brooklyn Bowl ... fans are pumped as she hits the stage -- along with Kane Brown -- to sing a last-minute rendition of her "1989"-era hit.
TayTay is totally vibing throughout the song ... strumming her borrowed guitar and shaking what her momma gave her as the crowd echoes the lyrics.