Taylor Swift wrapped up the 4th and final of her sold-out shows at the Staples Center in Los Angeles Saturday Night with a special guest.   She sang a duet with Jennifer Lopez.

Taylor told the audience that when she was a little girl, she'd sing in front of the mirror into a hairbrush.   She then announced that her hairbrush song was "Jenny From The Block."  Then, JLo appeared wearing silver sequins, and the two singers broke into "Jenny From The Block."

Swift later tweeted "Sang jenny From The Block w@JLo tonight at Staples Center.  STILL FANGIRLING OUT ABOUT IT."