Taylor Swift wasn't joking when she said she knows every word to Kendrick Lamar's "Backseat Freestyle." The singer celebrated 1.2 million copies of 1989 sold on Monday with a spot-on lip sync.

"Industry experts predicted 1989 would sell 650k first week," she captioned her Instagram video. "You went and bought 1.287 million albums. AND IT'S GOT ME LIKE:"

Taylor's love for Kendrick's music is reciprocated, because just yesterday, we heard the rapper doing his own rendition of "Shake It Off" during an interview with The FADER

“You can’t put great music in different genres,” he told The FADER. “I enjoy great music outside of my own music all the time, so I definitely can see where she’s coming from when she says that she listens to the record, and it’s a great thing for her to acknowledge that and put that good energy out into the world like that.”

In her Rolling Stone profile, Swift explained that "Backseat Freestyle" was her secret for keeping up her confidence.

“You want to know a trick to immediately go from feeling victimized to feeling awesome?” she said, whipping out headphones and clicking on the good kid m.A.A.d city track.

Well, with her third album in a row to go platinum in the first week, I'd know is a pretty good time to feel awesome.