Sean Penn not only puffed away on a cigarette throughout his interview with Stephen Colbert on Monday's Late Show—the actor gave the interview while still under the influence of a sleep aid. "I’m doing well," Penn said in response to Colbert's greeting. "You’ve inherited a little of the Ambien I had to take to get to sleep after a red-eye last night." Colbert pointed out Penn is always a bit low-key in interviews, wondering, "How do you tell Sean Penn on Ambien from Sean Penn not on Ambien?" Penn acknowledged, "I think it's pretty much the same."
Colbert, who provided Penn with an ashtray when he lit up, also talked to Penn about the cigarettes. "Please don't smoke anymore. I don't mind, I mean, my parents smoked when I was a child so it gives me happy memories to smell cigarette smoke. But, you know, we want you to be around for a long time and those things are bad for you," Colbert said. Penn's response? "This is job security for oncologists." Penn spent most of the interview, however, talking about his new book released Tuesday, Bob Honey Who Just Do Stuff, about a septic tank salesman turned assassin. Watch in our gallery or here. (Read more Sean Penn stories.)