While Joel sang "Uptown Girl," Lawrence, 25, and Schumer, 34, danced barefoot on the piano, and Lawrence even kissed Schumer's feet.
How did this pairing come about? Well, "Uptown Girl" is included in Schumer's film "Trainwreck," and the whole thing was planned.
Kim Caramele, Schumer's sister, filmed video of the actual concert, which she shot while standing behind Lawrence and Schumer on the piano.
The two actresses met a few months ago, and Lawrence told the New York Times that they're writing a screenplay together in which they'll play sisters.
"Amy and I were creatively made for each other," she said. " We have different flavors. It's been the most fun experience of my life."