She draws the number 13 on her hand with eyeliner each night before a concert.
Her drummer put a number 13 on his drum.
She was born on the 13th, turned 13 on a Friday 13th, her first album went platinum in 13 weeks, and her first number 1 song had a 13 second intro.
She says that whenever she is seated in row 13 or row M (the 13th letter) at an award's show, she always wins. And if she sees a 13, it'll bring her luck, but if she sees no number 13 that day, she'll lose at the award show.
In the film Valentine's Day her character gives her boyfriend a gift, his own shirt with the number 13 on the back, that her character's lucky number.
She plans her meet and greets to last for 13 hours. Although at the CMT music fest, she extended her planned 13 hours to 15 hours of autograph signing because of all of the fans.