The Tonight Show host had TV legend Bill Cosby on as a guest last night, with Fallon overwhelmed by the urge to start impersonating Cosby's distinctively - laid - back - way - of talking.
He told him; "Bill, I can't help but talk like you when I talk to you, Cause when I talk like you, I slow everything down. And start to talk like you. And I dance like you, and I do the moves like Bill Cosby does the dance moves."
All said in a fairly spot on imitation of the former star of The Cosby Show, with even some quirky Cosby-esque dance moves to boot.
Bill looked (comically) unimpressed and went to walk of to studio, with Fallon calling after him; "Bill, don't leave, now don't be upset, please!"
Watch below!
Later on, in keeping with the theme of extreme sports on the show, Bill Cosby agreed to tightrope the floor of the studio with Jimmy on his back...
