nyaff:
A disparaging term for a despicable or irritating person, especially one small in stature:
“Tell that wee nyaff Ah’m gauny boot his arse fae here tae Govan*.”
The word seems to derive from an older Scots term for the bark of a little dog. Interestingly enough though, Partridge’s Dictionary of Slang refers to a Parisian slang word gniaffe (a term of abuse for a man) which would have a similar pronunciation. Perhaps the Académie Française would cite this an example of the Auld Alliance corrupting the French language.
Incidentally, this word is a favourite of my Mum’s.
* Govan is an area of Glasgow.
a Brit different 
It’s a favorite of my dad too. He’s from Motherwell and we’re all from Irvine but moved to the east coast when I was 9. It’s not so much an east coast word.
We used to stay with friends who lived right across the street from Ibrox stadium in Govan. I’ve never witnessed so many drug raids in one place in my life before.