Brian Regan taped his 20th appearance on The Late Show with David Letterman on Monday afternoon, and it’ll air tonight, with Regan hilariously describing how he fakes his massive amount of expertise about art. His appearance helps promote his upcoming hour special on Comedy Central, "The Epitome of Hyperbole," that debuts 10 p.m. Sept. 6 (and available as a DVD with extra footage on Sept. 9). I chatted with Regan after his Letterman taping in the green room, and despite my amazingly artistic camera angles, you’ll still be able to hear Regan explain the peculiarities of performing stand-up for a TV audience, including how the cameras and applause meters all make a difference in telling jokes. Watch our chat:

Related: His theater tour continues Sept. 4 in Joliet, Ill. Buy tickets for Brian Regan here.