NC-17 is a rating of the The Motion Picture Association of America which stands for No Children Under 17 Admitted. It is also used within the fanfiction community to indicate the level of adult-oriented content. It means that the story contains either graphic violence and/or nudity and sexual content.
Just Between Wikis articles containing such content also carry this warning, though no main article is permitted to carry this content. It is only allowed on separate articles or subpages of main articles. These carry the NC-17 rating and by accessing these articles the user is confirming his or her age to by above the legal adult age of his or her country or area.
This rating is to be taken seriously by all those reading articles on Just Between Wikis that carry such a rating. Be responsible while surfing the net!