N'arsed is short for Not Arsed!

A person using the word "N'arsed" are usually that not arsed that they can’t even be bothered to pronounce two words so it comes out "N'arsed"
Andy - Scotty mate, why did you just put that window through on a building we always socialise in?

Scotty - N'arsed!
by JuiceBox23 May 13, 2009
Get the N'arsed mug.