In "A Dance With Dragons", Roose Bolton tells Theon Greyjoy that he should say "my lord" like there is mud in his mouth. I read the books in Turkish and this passage did not seem to translate well.
Why would he tell him this? What does it mean?
The full quote is:
He did not understand. “My lord? I said—”
“my lord, when you should have said m’lord. Your tongue betrays your birth with every word you say. If you want to sound a proper peasant, say it as if you had mud in your mouth, or were too stupid to realize it was two words, not just one.”
Roose is chastising Reek (Theon) for sounding too posh. His concern is that no-one will believe that he's a simple servant if he uses the full version of the phrase "my lord". He urges him to slur the words together to sound more like m'lord.
The reason why he says to say "m'lord" is that's how a peasant would pronounce it a nobleman would use the "my lord" which Theon is still using even though he is now Ramsay's...umm..."pet"(?).
Okay as for the "mud in the mouth" part of the lesson. Nobles when talking to one another are meeting as equals and are expected to use proper speech, make eye contact and other things like that. Meanwhile, a peasant speaking to "his/her better" is basically expected to cower in fear. That means look down, mumble and all body language and speech should be submissive.
Over time the submissive speech of peasants has formed what is almost a second dialect of a language. In this case we have the word "m'lord".