Here are some more expressions I use for my expanded Westerosverse.
-Leftcarlot: old rank for lieutenant in most kingdoms of Westeros. Was traditionally a high officer of the military. The Reach used "lieutenant" instead of "leftcarlot," which can be considered a form of shibboleth.
Etymology... "Left:" obvious (the opposite of "right"). "Carlot:" from an old Swedish word for "free man," English form taken for a Wilde tale, used to refer to landowners: "[···] and the carlots would not suffer [···] even to sleep in the byres lest [···] on the stored corn, [···] and their hired men drave [···] away, [···]." The inspiration was the rank of "lyftcarl" (same etymology) in the Calvarian army from Witanowski's The Reynard Cycle.
-Maiden's cunt! An oath that refers to the goddess of love and her private parts. Can be an exclamation of rage, surprise, or any other intense emotion.
-Sunflower/Snakeflower/Sandflower: slurs to refer to a person of mixed Dornish and Reachish descent; "sandflower" is used if the mixed-race person was conceived outside wedlock, by the lovechild surname of both regions.
-Firewater: brandy (term used mostly among non-Reachers and in the military).
-The Uns: the Dornish (Reach slur, due to the tripartite motto of Dorne and House Nymeros Martell).
-Lightriders: Dornish officers (Reach expression), due to their lighter scale armour.
-Sun-snakes/southern snakes/snakefolk: the most common slurs for Dornish people in the Reach and Stormlands (from the Dornish scale armour, use of chemical warfare, and ethnic stereotype).
-The Dornish sickness: refers to the consequence of a common strategy in Dornish warfare among the enemy. Upon invasion, the Dornish usually resort to scorched earth tactics, fleeing their communities, taking their crops with them, and poisoning their sources of freshwater to take on the thirsty enemy. The combination of sunstroke and this neurotoxic poisoning is what Reacher maesters call "the Dornish sickness." It is generally lethal.
-Lightning smite them!: The typical Stormlands curse.
-May a left-handed Dornish spear pierce their heart!: far less common curse, more common in literature such as wartime and romance ballads.
-Flower-eaters: Reachers, Dornish slur to refer to them.
-Fairfaces: another Dornish slur for Reachers.
-Kettleheads/Kettlechests/Kettlemen: a third slur for Reachers used in Dorne, due to their heavy armour. "Kettlemen" is the most common Dornish slur for Reachers.