To be and/or act bizarrely weirder than normal.
If your friend normally teases and jokes around with you
and one day he decides to throw snowballs at you...
while your on an ice-rink
...he would be considered a neuch
It is not meant to be an insult, but more of a joking name. Like when someone calls you a freak, your not actually a freak (in some circumstances) you're just a lil weird :)