Citations:knocker

Noun: "device used for knocking on a door"

 * 1843 — Charles Dickens. A Christmas Carol.
 * And then let any man explain to me, if he can, how it happened that Scrooge, having his key in the lock of the door, saw in the knocker, without its undergoing any intermediate process of change — not a knocker, but Marley's face.
 * But there was nothing on the back of the door, except the screws and nuts that held the knocker on, so he said "Pooh, pooh!" and closed it with a bang.

Noun: "breast"

 * 2014 August 20 – u/zerosuitanon (username), "Long-ass shitpost about Samus' Zero Suit. Ignore if you want." in r/Metroid, Reddit, retrieved May 9, 2020.
 * Does [ Samus Aran] have big, fake knockers? I don't think so. It seems like they would get in the way of her line of work. So why are her boobs sticking out when the Zero Suit should, by all rights, be holding them down?