Joe Miller

Figure of speech. When Lenehan ends his limerick "I can't see the Joe Miller. Can you?" he means that he can't see the joke, since Joe Miller was a comedian. This exemplifies the rhetorical principle of antonomasia: substituting a property for a proper name, or vice versa.

John Hunt 2023

Title page of the 1739 edition of Joe Miller's Jests, scanned from a 1963 Dover facsimile. Source: Wikimedia Commmons.