A random person who tags along with groups of people who he never usually interacts with. Occasionally he will speak up, and everyone in the group will look at him funny because no one is friends with him.
This term was created students 10 years ago to insult random people whose intrusive behavior resembled a science teacher named Mrs. Neff
There was this random neff Mendy's party the other night who started talking about how beer is bad.
Nyaff is a word used mainly in the West of Scotland; especially around the Glasgow area that is used when referring to someone who is a bit weird or 'off' or just to refer to someone who you don't like in general.
Bob: Ahm no too keen on that Tam ae, he's a wee nyaff so he is.