Jennifer Lawrence and Amy Schumer perform 'Uptown Girl' with Billy Joel

Jennifer Lawrence and Amy Schumer have become fast friends this summer. They vacationed together in the Hamptons and have now showed up in Chicago where they hopped on stage with Billy Joel at his Wrigley Field concert on August 27.

Inside Amy Schumer writer Kyle Dunnigan posted video on Instagram of the gal pals dancing barefoot on the musician's piano, even singing "Uptown Girl" together. The Hunger Games star at one point even gave Amy's foot a kiss.

Amy and Jennifer danced on Billy Joel's piano at his Chicago concert Photo: Instagram/@amyschumer

Amy and Jennifer didn't take their appearance lightly and prepared for their big moment on stage by rehearsing with the music legend earlier in the day. "Rehearsals a little rough," Kyle wrote alongside a video of the private rehearsal. "Get ready for a bunch of billy joel photos. Me amy schumer and jennifer lawrence are going on stage tonight." The video was from the rehearsal was later deleted. Amy's sister Kim Caramele shared a video as well of the whole group doing the can-can and performing a choreographed routine. "Thursday's with @caramelodies @amyschumer @kyledunnigan1 Oh and jlaw," she wrote.

Despite meeting only a few months ago, the actresses have quickly become friends. Jennifer revealed the pair is even working on projects together. "We're almost done writing. It just flowed out of us. We've got about 100 pages right now…Amy and I were creatively made for each other," the 25-year-old told the New York Times.

Just another night on stage with Billy - with @kimcaramele @amyschumer @kyledunnigan1 jenniferlawrence #billyjoel #wrigley
A video posted by @caramelodies on Aug 27, 2015 at 9:44pm PDT

"We have different flavors. It's been the most fun experience of my life. We start the day off on the phone, laughing. And then we send each other pages. And we crack up," she continued. "I'm flying out tomorrow to see her in Chicago. We'll write a little bit with her sister, Kim, who worked with Amy when she was writing Trainwreck."

Meanwhile, Billy welcomed a baby daughter Della Rose Joel into the world earlier this month with wife Alexis Roderick.