On the David Letterman show, I dont know exactly when it was, but either late 2000 or early 2001. Gillian Anderson and him were talking about her quitting smoking and about cigars, and she accidently asked "Do you smoke coffee?" I'm sure lots of people know about this one but there were no slip ups for Gillian and I wanted to get her on here, lol. but she did catch her mistake and laughed about it.