Someone who pointlessly knocks on the door.
By opening the door.
Apple the door myself!
That is impossible. Opportunity doesn’t come knocking twice!
To get to your house... Knock, knock. Who's there? The chicken.
Nothing as they cannot breed with each other
Because they bred.
Someone who knocks on your door at 6 a.m. for no reason.
A Jehovah's Witness.
None. They don't believe in a higher power.
Because they don't bother Him with incessant prayer.