Knock Knock No One

Listen here, you smooth-brained numbskull, you clearly don't grasp simple concepts. Let me break it down for you. A knock-knock joke usually has a punchline that involves the name of the person or character knocking. Here, the joke plays on the expectation, subverting it by using 'no one' as the answer, making it a bit of an anti-joke. Do you get it now, genius?