Knock, knock.
Who's there?
Natyourcheese.
Natyourcheese who?
Natyourcheese, I wasn't gonna say bless you!
Knock, knock.
Who's there?
Natyourcheese.
Natyourcheese who?
Natyourcheese, I wasn't gonna say bless you!
Listen up, buttercup. This joke relies on wordplay. "Natyourcheese" sounds like "Bless you" after someone sneezes. But the person telling the joke doesn't want to say bless you after you sneeze you uncultured swine.