Picture this: A young Taylor Swift looking into the mirror and, with a hairbrush in hand, she begins to belt out Jennifer Lopez's 2002 pop hit "Jenny From the Block."
The 23-year-old pop star told a crowd of fans during her concert in Los Angeles on Saturday, Aug. 24, that's what she used to do, calling the tune her "hairbrush song." Swift then introduced Lopez on stage as a surprise guest so that the two could perform the song together. Video of their performance can be seen below.
Lopez is just the latest singer to stop by as a guest performer on Swift's Red tour. Past guests include Carly Simon, Tegan and Sara and Ellie Goulding.
Lopez appeared on stage behind Swift wearing a sequined New York Yankees cap, a matching sleeveless shirt and pants. Swift and Lopez were joined on stage by male backup dancers and Swift got the chance to show off some hip-hop dance moves.
At the end of the performance, the two singers hugged and Lopez gave Swift her Yankee hat.
"Sang Jenny From the Block with @JLo tonight at Staples Center. STILL FANGIRLING OUT ABOUT IT," Swift tweeted on Saturday.
"@taylorswift13 had so much fun with you tonight!!! #RedTourLA #jennyfromtheblock #hairbrushsongs," Lopez tweeted to Swift.
Lopez also posted photos of the two posing together backstage on her Instagram account.
On Aug. 20, Swift was honored for becoming the first solo artist to have sold out 11 concerts in total at Staples Center.
Check out an Instagram video the Staples Center posted of Swift and Lopez's performance and a fan video from the concert below.