Tina Fey's "Lip Flip" Slip
The former SNL "Weekend Update" cohorts decide to do a bit in which Fey's lips are superimposed on Fallon's face, and vise versa. ("Lip flip," get it?) Once they try to do a duet of "Endless Love," however, thinsg quickly devolve into one big giggle fit. We'd forgotten how much we loved seeing these two making each other laugh.