If you've ever wondered what famous people are whispering to each other while the flashbulbs pop, Jimmy Fallon's alter ego Peggy Hess is here to help. Taking a cue from the brilliant Bad Lip Reading series on YouTube, Fallon dressed up as a creepy British talk show host on The Tonight Show Wednesday to decipher several private conversations that happened in public.

First up was Jessica Chastain and Matthew McConaughey at the American Cinematheque Awards. It turns out Chastain wasn't congratulating McConaughey on being a recipient—apparently she was trying to convince the actor that she made up the song "Waterfalls" by TLC.

Other revealing moments include Emily Blunt and Josh Brolin making fun of Benicio Del Toro's duck face, Jack Black letting slip a fear of frogs, and Dwayne "The Rock" Johnson crushing someone's rib cage at the Hercules premiere. Click the video above to hear Kate Moss's supposed "knock knock" joke that made Cara Delevingne crack up.