Most of the big laughs on The Tonight Show come not from pre-written jokes or clever monologues but from the mischievous little games Jimmy Fallon plays with his guests. The latest such game is “Lip Flip,” which is pretty self-explanatory: Fallon and his guest—in this case, Ricky Gervais—use some digital manipulation to switch mouths, and then take turns imitating, parodying, and generally mocking each other.
It sounds silly, and it is—but Fallon and Gervais know that, and it doesn’t stop them from producing around five minutes of giggle-inducing hijinks. If anything, watch for the raucous duet of “Little Drummer Boy.”