Stephen Colbert Fixates on Andy Cohen's Open Mouth

By: Michael Matson

Watch What Happens: Live host Andy Cohen stopped by The Colbert Report Monday night to promote his new memoir, Most Talkative, which is what Cohen was voted in high school (along with "Biggest Gossip").

During the course of the interview, Colbert becomes obsessed with Cohen's mouth, which is open on both the front and back photos of the book's dust jacket, as well as inside the memoir. Colbert then tests Cohen to see how long he can sit comfortably with his mouth closed.

Watch the hilarious results below.