NSFL also known as NLS means Not Safe For Life or Not Life Safe normally referring to a link someone or some website has sent you meaning no one should ever see it.
by Kelby Raper January 28, 2008
Not Safe For Lunch. A warning that linked content is sufficiently horrendous as to be sensibly avoided by the weak of stomach.
This website|image _link_ is NSFL.
by Morosoph October 12, 2008