'Excuses' such as illnesses, not producing enough breast-milk, being on certain medications etc are often looked over by the more militant nazis.
Apparently, no Boob Nazi has ever, ever made a parenting mistake. To suggest otherwise is heresy.
For such dedicated parents, Boob Nazis seem to spend an awful lot of time condemning people on LJ, and making user pics of their saggy tits and ugly brats.
Applies to any female wearing clothing that either directly covers their bare, chest region and/or clothing, usually loose fitted or of very thick material, that hides the natural curvature of said chest region.
Can also be applicable to a female whom, after being asked to reveal her boobs, refuses to do so.
Important: The female subject must possess boobs in which one actually wishes to see (i.e. an old woman with sagging boobs would not be eligible for this title).
Girl: Oh my goodness, no!
Boy: You're such a boob nazi...
Like the word "cunt" (ref: "Vagina Monologues"), it has been captured by breastfeeding mothers and used as a term to describe a mother who cares enough to be passionate about giving their children the best and healthiest start in life.