Girl can sang...well, sorta! Lena Dunham got very invested in her lip sync battle with Jimmy Fallon when she appeared on The Tonight Show on Friday, June 12. 

The Girls creator and star, 29, came out wearing a miniskirt and tracksuit jacket. 

"You're all sporty!" Fallon, 40, declared. 

"Well, I wanted to take this seriously, and I needed room to flex," Dunham happily replied. 

And she certainly did. Lip syncing her first pick, "Outside" by her real-life friends Calvin Harris and Ellie Goulding, Dunham slid on her knees, thrusting her pelvis forward to the audience. 

What she lacked in lyrical knowledge, Dunham made up for in passion — at one point grinding on Fallon, who stepped back exclaiming, "I'm a father!"

Following the performance, Dunham tweeted the clip, writing, "Lip sync battling my #1 teenage celebrity crush is now crossed off the to-do list. Luv ya." 

Watch the video now to see both celebs' performances! 

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