To nem (verb) is to complain or shout about something - usually about a petty or trivial reason.
A nem (noun) is like a rant where the above takes place.
âCan I come round to yours today?â
âCanât sorry, mumâs nemming cos i forgot to take out the dishesâ
OR
âIs Poppy alright?â
âSheâs fine, I just accidentally tripped her up so sheâs having a nemâ