10 celebrities Taylor Swift has brought on stage for her tour (+Photos)

5. Avril Lavigne

Things felt anything but “Complicated” when Taylor surprised the crowd at her August 29 show at PETCO Park in San Diego with Avril Lavigne, bringing fans to their feet with excitement. Before bringing her onstage, Taylor noted to the crowd, “We’ve been texting all week and we finally got to meet today and she’s so cool. She’s so sweet, which I love, when I find out that one of my favorite artists is also super amazing as a person.” The two sang Avril’s 2002 hit song “Complicated,” and Taylor later tweeted that it was “incredible sharing the stage” with Avril. And Avril went on to say, “such a pleasure to perform ‘Complicated’ tonight with @taylorswift on her #1989 world tour! She rocks.”