The phrase is not needed to be said by the person who has just insulted, offended or somehow taught a lesson to the other. In fact, 'narnenar!' is quite better when used by a person nearby.
Just as well, 'narnenar!' can be used as 'narne-narr?', in case an attempted insult makes no sense at all or is introduced with a flurry of stuttering and shames the person just as easily as it would regularly.
Dude2. "You dont even know my Mom's name."
Dude1. "Well obviously, she was screaming MY name."
Dude1. "Oh yeah, well, if my Mom does the sucking, then your dad sucks me off just as we-ll?"
Dude2. "Dude, I know my Dads gay, why are you into that stuff. Most uncool."