That category is intended for sexually explicit questions really, but what happens is any time you use a word that cannot be shown with the filter, the question posts, but it gets sent to matter. If you asked a question about apple ju1ce right now (spelled correctly), it would get sent to mature because ju1ce doesn't pass the filter. In doing this, people that post answers to mature questions can post mature answers too. The question and all of its answers are not bound by the filter because they are "mature" and not out in public viewing.
This also helps with ads because they can't be placed on anything with mature content. Although us logged in users wouldn't see it, those that are just browsing around would. If the stuff goes to mature, no ads show up and people can say whatever they want. The question just isn't easy to find.
Nothing that makes you roll your eyes and think "He/she is so imature!"Some people here are acting like two-year olds =/
most things i post apparently