Taylor's done it again!  It seems she does this at all of her shows.  She will pick another artist's song and perform it acoustically.  This past weekend she was playing the Staples Center in L.A. and covered her friends song "Realize", originally sung by Colbie Caillat.  Colbie was at the show and during the performance she tweeted,
What an amazing night at Staples Center watching @taylorswift13! She was gorgeous & wonderful. & sang my song "Realize" so beautifully! ♥"
Catch Taylor's performance right after the jump.