"Animation is simply a form of expression, and can be used to great effect for any genre or target audience," said Sam Matthews, the son of a children's film maker. 

Matthews watched animated shows and movies growing up (as many of us did), but his tastes have changed with his age (as many of ours have.)

 "Western culture has come to regard animated media as being strictly for children, but influences from other cultures are starting to shift this trend for westerners," said Sam. More and more animated shows and films are being created to be entertaining for adults watching it with their kids, and some are even being created for adults only. Adult Swim is an entire network created to showcase (mostly) animation  targeted at adults. However, most of these shows seem to be targeted at inebriated 16-29 year olds, and it barely skims the breadth of the history of adult animation. 

You've probably heard of South Park and The Simpsons, and the whole line up of Seth MacFarlane shows (Family Guy, American Dad, The Cleveland Show). There is also a huge amount of anime targeted towards adults. Here is a list of the top 6 western shows and films for grown-ups that you may not have heard of, but which are fairly great. 
*Also, recognize that the clips are to various extents NSFW!*

6. Clone High 
Why it's for adults: It's about historical figures children wouldn't remember. Some references to beer and sex.
Why it's great: Clone High was a series that ran for one season about teenage clones of historical figures, like Abe Lincoln and Ghandi. The characters were well-developed, and the humor was at once understandable and smart (In shop class, Caesar warns a careless clone of Jesus Christ, "Be careful with that nail gun, Jesus!")
5. The Plague Dogs (1982)
Why it's for adults: Animal abuse, some violence, sad ending.
Why it's great: The Plague Dogs was written by the same author of Watership Down, and it follows the escape of two dogs from a testing facility. The film features an attempt to escape human oppressors, a descent into insanity, and a terribly emotional ending. 
4. Superjail! (2006-2008)
Why it's for adults: Extreme violence, references to sex and alcohol.
Why it's great: Superjail! is a series on Adult Swim with incredible, psychadelic animation. Each episode starts with a somewhat benign plot in a super huge jail (in a volcano in another volcano), but things soon go awry. Colors swirl, insanity ensues, and the inmates are massacred in terrible, bloody numbers, but it's completely hilarious in the emphatic randomness.
3. Spicy City (1997)
Why it's for adults: References to violence, sex, and drugs, language
Why it's great: Spicy City was the first animated adults-only show, created by cartoon bad-boy Ralph Bakshi. What's noticeable here is not the animation or the adult themes but the intense philosophical issues related to the mind and body. In one episode, characters who are in love destroy their bodies to exist together in a virtual game, and in another a man searches for his daughter but accepts a clone as substitute. If any series will make you think, it's this one.
2. Ren and Stimpy "Adult Party Cartoon" (2003)
Why it's for adults: Gross humor, smoking, references to sex
Why it's great: Yes, it may be hard to believe that the beloved cartoon series of your youth was made into a short series for Spike TV, but the result was at times pretty great. While some of the episodes are reminiscent of the gross humor for which Ren and Stimpy are famous, (taken to an even higher degree,) the more adult humor was even funnier. The most amazing part of this series, though, was the incredible animation. The characters' actions are emphatic and humorous, and their elasticity and caricaturized faces demonstrate real mastery of animation.

1. Fritz The Cat (1972)
Why it's for adults: Sex, drugs, violence
Why it's great: Fritz the Cat was well-known when it came out, as it was the first X-rated animated feature film. The story involves a college student, who is also a cat, who is caught in the 1960's intersection of sociopolitical activism and hedonism. While the adult elements are salient, the plot is very good as well, and it should make you think. It was directed by Ralph Bakshi, and it marks the historical moment when western animation extended its reach to adult humor and themes.
"Even with realistic treatment of the subject matter, an animated format disconnects the audience from their preconceptions, and allows purer emotional connection between the audience and the story teller," said Matthews.

These pieces are alternatively humorous, beautiful, insane, shocking and emotional. Hopefully these examples exemplify the reasons that adults can enjoy cartoons just as much as our younger selves.
  Controversy over free speech has apparently bred some sort of genre of film in which the material focuses on trying to be offensive. There have been a substantial number of shows and movies which are teeming with violence, drug use, sex, and stereotypes, exaggerated in a way that can only serve to push the boundaries of free expression. For some reason or another, a large portion of the more salient examples of purposely offensive material appear to be animation. Perhaps it's because it's easier and less unpleasant to animate certain terrible actions, or because it makes an even stronger point to make what is sometime's regarded as a children's medium offensive. Maybe it's because you can animate physical traits that are racially insensitive ("darky" iconography, buck-toothed asians, busty women), or maybe I just noticed it because I love animation.

To start, there was the movie Salo, or 120 Days of Sodom. When it was first made, it was considered the most offensive movie of all time. It was the product of a book so full of depraved sex, even /b/tards might have a hard time reading it, and it was coupled terrible messages. Marquis DeSade, the author (from whom the word Sadism comes), was jailed for his perverseness.

Ralph Bakshi created the first X-rated animated film, Fritz the Cat. Since then, his animated films have generally not been targeted towards children. Probably the most overt example of this would be his movie Coonskin, aka Street Fight. The movie is a parody of the controversial Song of the South but is 100 times worse, full of black caricatures who occupy the roles of mob boss, preacher, exploiters of religion, exploited athlete, crazy homeless man, and pimp to name a few. There is surprisingly little controversy surrounding this film, perhaps because Bakshi made it clear from the sheer extremeness of the film that it was trying to be shocking and mock darky iconography. Here are a few clips set to the opening theme:

It's hard to say, but Bakshi may have contributed to what I can only describe as a sub-sub-genre, of black animated characters which are far from PC, made by black artists. A popular example is Aaron McGrudger's The Boondocks.

Read a Book is a parody of the schools trying to appeal to kids to get messages across.

T-Pain and other rap artists recently made this movie, called Freaknik the Musical:

  Borat and Bruno are probably good, but still very contentious, examples of making stereotypes look ridiculous.

South Park has tread on this topic multiple times, and has been controversial as of late. There were a few episodes that focused on offensiveness (mostly swearing) and then the movie South Park: Bigger, Longer, and Uncut, focused on that theme. The most recent episodes (200 and 201) did not try portray the most offensive cumulation of vile images possible, but one of the most contested images of all time, that of the Muslim prophet Muhammad. The image of Muhammad, the word "Muhammad," and a speech on why media shouldn't give into intimidation by extremists (not about Muhammad), was censored by comedy central.

Recently, the Direct-to-DVD movie called The Drawn Together Movie: The Movie came out, based on the discontinued Drawn Together TV series. In the movie, the characters run around doing many disturbing things, for apparently no reason. With the help of a character that is a parody of South Park, they search for a "meaning" to accompany their perverseness, which will supposedly help them not get canceled. In the end they decide that there need not be a reason or a message behind offensive television, which is ironically a message in itself.

Some would say that these pieces are a detriment to free speech, in that they are a flagrant abuse of the right and a reason to make restrictions. In my opinion, purposely offensive films are extremely important to free speech in that they keep the boundaries pushed, and they affirm that even when this offensive material is produced, it is still harmless. Even if the films themselves don't make a point, they keep the path clear for anyone who does want to make a point using offensive methods.