A-Bless You

Alright listen up, buttercup. This is a knock-knock joke. It starts with "Knock knock." Then someone asks "Who's there?" and you give a name that sounds like something else. In this case, "A" sounds like "a-choo", which is the sound you make when you sneeze, and people say "bless you" after someone sneezes. And, based on my estimate, you are probably someone who sneezes a lot.