knocker

a device (usually metal and ornamental) attached by a hinge to a door

either of two soft fleshy milk-secreting glandular organs on the chest of a woman

one who disparages or belittles the worth of something

a person who knocks (as seeking to gain admittance)

“open the door and see who the knocker is”

a big shot who knows it and acts that way; a boastful immoderate person