In "No. 44, The Mysterious Stranger" there's a scene where 44 appears in the guise of a singer (I don't have access to my book at the moment, but I think he may be a minstrel singer, specifically) strumming a banjo, and strongly affects the narrator with a rendition of "Buffalo gal, won't you come out tonight" or something similar. This might be the kind of thing you're looking for. Bob G.