VIDEO: Ricky Gervais Can't Keep a Straight Face During Lip-Flip with Jimmy Fallon

It's official: as an interview subject, Ricky Gervais is pretty much up for anything.

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The Derek star stopped by The Tonight Show this week and humored Jimmy Fallon with a game of Lip-Flip, in which Fallon's and his interview subject's mouths are superimposed on one another's face. They then proceed to talk about shaving their genitals, and perform a duet of David Bowie and Bing Crosby's version of "Little Drummer Boy" — and Gervais can barely keep it together the whole time.

It's pretty hilarious, though we're wondering what prompted Fallon to give Gervais a Southern accent? Whatever, it works.

Check out the game below: