Alright so I like to think that after Thorin and Bilbo get married and are happily ruling the kingdom of Erebor together, they begin to teach Bilbo khuzdul. When he’s first learning, he would carry around a little list of some useful words and phrases he might want to use that maybe Ori, Balin, or what-have-you helped him make.
So one day at a council meeting, Bilbo is trying his best to get Thorin to go through with a trade deal between Erebor and the Elves of Mirkwood that would mutually benefit both kingdoms. However, the king (as to be expected) REFUSES and borderline throws a fit, ranting about elves and disloyalty and betrayal and blah blah blah. Bilbo is frustrated, but he knows his husband well and he was anticipating this reaction. So he pulls out this lil’ list of khuzdul and says the words for things like “please?” and “it’s good for Erebor”, etc.
Thorin definitely cools down, loving the sound of his native language on Bilbo’s tongue, but this hatred for the elves is fierce and Thorin doesn’t budge in his answer at all (halfway sticking to his feelings about elves, halfway conning his husband into speaking more khuzdul). Bilbo eventually becomes so utterly done with his husband that he reaches into his waistcoat pocket and pulls out a second list. He’s fuming when he recites clearly the khuzdul words for “pig-headed!”, “stubborn!!”, and “childish dwarf!”, before storming out of the room to get away from politics for the moment.
Thorin is left speechless, and his cheeks turn pink with embarrassment, because his beloved husband just pulled out a prepared list and used his own language against him and worst of all, he kinda liked it.