The general consensus among People Who Watch Things(TM) is that animated series are for kids. But are they really? Even when you carefully examine the so called "cartoons for children," you can find tons of incredibly inappropriate things hidden in them.
And let's be honest - we live for it. We live for all the dirty jokes, sexual inuendos, and sneaky puns. And TV producers know that only too well. Hence the genre of adult animation. And let us tell you, there are some excellent adult cartoons out there... EXCELLENT.