Several of my friends had read this, so I got curious and peeked, and I had this moment of EXTREME PEDANTRY that I just can't put aside. THIS WILL BE TEDIOUS TO EVERYONE BUT ME, but here goes: 
 Sinsar Dubh. I can accept "doo" as a regional pronunciation of "dubh" (though I myself would say "duv" -- that may be a Munsterism). But "Shi-sa" for "Sinsar"? That makes no sense to me as Irish. There are lots of silent consonants in Irish, but N and R are not silent. It also violates the broad-and-slender vowel rules, but sometimes Old Irish spellings do that, so I'm not fussed. I can't conceive of it not being pronounced "shin-sar", though. Does she mean "sinsear" (shin-sher) -- ancestor? 
 Now, maybe the first word is not intended to be in Irish. OK. But the second word is plainly Irish for "black", so it seems fair to treat the first word as if it were Irish without further explanation. 
 (Is there further explanation in the books? Or even later in this scene? I never actually got to the sex because I was so busy being a self-important dork.)