The mentally challenged are emotionally unstable and utterly helpless. They do not respond well to slaps in the face, running faucets, or being dropped off on the side of the road because they wouldn't stop crying in the back seat. If a smoke alarm goes off, they don't, as you or I would, say to themselves, "Where is that unpleasant sound coming from? What is causing it to make that sound and how can I disable the appropriate mechanism?" No. They just run around screaming like retards.
Retards are very inconsiderate. If they had the slightest regard for the happiness of their parents, they would have wandered off years ago. In addition to their horrible table manners, they lack adequate conversational skills and rarely (if ever) remember the names of new acquaintances, all of which can reflect poorly on you. When introducing the travesty to others, make sure to point out that your dirty, self-absorbed moron of a child was born that way.
Though the thought is humorous, mentals should not be having sex. In fact, it' probably illegal. Sure, you could videotape your child and its love interest having sex and sell the video on eBay for, say, $49.99 with a title like "Mongoloid Love" or "Ass-Fucking on the Short Bus." But God only knows what the child of two retards would look like. Furthermore, they're just as likely to be sexually attracted to stuffed animals and rocking chairs as other "human" beings.
When you suffer a nervous breakdown and lose your job because your twelve year old child can't read and eats glass, at least you won't have to wait around at the unemployment office. Just parade the little goofball around on a leash and skip to the front of the line at liquor stores, gun retailers, and racetracks.
In conclusion, having a mentally retarded child is a fate far worse than death, which means that life can't really get any worse for you. Paralysis, stroke-induced blindness, bankruptcy"all of these tragedies pale in comparison with having a 19-year old son whose favorite color is "dog." So cheer up! God can't fuck you any more.