An acronym for "Nose Laugh", the short involuntary blast of air from the nose when you read something funny. Used when something is mildly amusing and air expels from your nose, but isn't funny enough to make you actually LOL, or "laugh out loud".
An abbreviation for the phrase "no lie" often used via IM, Facebook status, tweet or text (or any form of written communication). Not usually said in person, unless you're a loser.
NL is an abbreviation used in the cannabis growing culture for the "Northern Lights" strain which is quite popular for both commercial and personal grows because of its size, yield, hardiness, ect.