[ougawouga]

Couldn't tell if the writer was being subtlely ironic about the origin of the term poop deck, but presumably it's some kind of play on the nautical phrase "poop deck". The latter term originates from "la poupe", which is the French word for "stern".

[swang]

I think you're just misunderstanding. He is not talking about the origin of the word, "poop deck" in normal English vernacular. He is referring to why these Cardists call worn out decks, "poop decks": because the video referencing the "poop deck" was shot in a bathroom with his bathroom deck he keeps in there