A: The "poop deck" of a ship is the raised platform at the back that forms the roof of the aft deck cabin. The back end of a ship (the aft end, in naval parlance) is called the stern (as opposed to the bow in front), and the word for stern in French is la poupe. Ha ha. Poupe. At any rate, the poop deck was where the helmsman stood to steer the ship, as well as the captain and his officers when they weren't occupied elsewhere, since the raised perspective gave an excellent view of the the deck, the rigging, and the horizon in all directions. As the poop deck was the command center, where all the most important decisions radiated from, maybe this is the root of the term "the straight poop".
Why the English, constantly at war with "Pierre" across the channel, tolerated naming an important part of their ships with a French term is hard to imagine. Maybe the average sailor just didn't know that they were doing so, and the officers were too well-bred to make a fuss about it. Maybe it was simply that everyone on board was constantly on a low-level drunk from grog and so used to weird naval terms like "scuppers", "larboard", "bowsprit" and "figgy dowdy" that "poop" didn't sound unusual.
