knocker

(noun) (Yiddish) a big shot who knows it and acts that way; a boastful immoderate person.

(noun) a person who knocks (as seeking to gain admittance). Example: "Open the door and see who the knocker is."

(noun) one who disparages or belittles the worth of something. Synonyms: detractor, disparager, depreciator.

(noun) either of two soft fleshy milk-secreting glandular organs on the chest of a woman. Synonyms: breast, bosom, boob, tit, titty.

(noun) a device (usually metal and ornamental) attached by a hinge to a door. Synonyms: doorknocker, rapper.