VIDEO : David Letterman Yells at Strangers on 'Billy on the Street'

Ever since Funny or Die's Billy Eichner made David Letterman crack up during his Late Show debut, the soon-retiring host was bound to join the rising comic on the cult-favorite series Billy on the Street . "I'm out here with the new host of E!'s Fashion Police, David Letterman," quipped Eichner at the start of the hilarious video.