Stands for Non-Cyber Laugh, in which a joke told over an instant messenger, text etc. makes the receiver physically laugh. Not the same as lol or lmao, as the person is, more often then not, not laughing at all but feels they have to say lol.
Mel: So who is Bronze?
Mitch: Gold, Silver, whatever you want to call the flop.
Mitch: Settle. It wasn't that funny.