In Amy Schumer’s new movie Trainwreck, there’s a recurring joke based on Billy Joel’s “Uptown Girl.” And when Joel played Chicago’s Wrigley Field last night, Schumer was there, with a very good friend, as WGN reports. Schumer and fellow movie star Jennifer Lawrence are tight, and Lawrence tells The New York Times that they’re working together on a screenplay for a new movie in which they’ll play sisters. Onstage at the Joel show, Schumer’s sister Kim, who’s helping Schumer and Lawrence write the screenplay, was also up onstage, as were some others. But the big moment came when the two celebrities danced barefoot on top of Joel’s piano. They also rehearsed their routine with Joel in an empty Wrigley Field earlier in the day. Watch some footage of the performance and the rehearsal below.

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A video posted by @amyschumer on Aug 28, 2015 at 6:10am PDT

Jennifer Lawrence and @amyschumer at the Billy Joel concert today! ❤❤❤💜 #JenniferLawrence [Co-owner•Frida]

A video posted by 🍞 (@thedandelioninthespring) on Aug 27, 2015 at 9:47pm PDT

Jennifer Lawrence with @kyledunnigan & @amyschumer today at the Billy Joel concert in Chicago! (via @jlawspanish) pic.twitter.com/4fbDbuPFYG

— Jennifer Lawrence (@JLdaily) August 27, 2015