Question: Doctor Tate, I was told that I have Diminished Gluteal Syndrome, but I've never heard of that. What does that mean?
Answer: You have no ass.
If you were Hank Hill from the popular television series King of the Hill, you would have heard the above answer from your doctor. However, as you aren't Hank Hill, and as King of the Hill is a cartoon show and not the real world, you wouldn't have heard it. In fact, if you asked your own medical professional they would have informed you that DGS is a fake syndrome and does not exist. Under that fake condition - one completely made up by KOTH's writers - Hank had no "cushion" back there and had been sitting on his spine. If it were a real syndrome, the cure would be simple: doing what you're doing now and surfing the web with a big plate of donuts in front of you. However, in Hank's case he wore butt implants, also known as "butt-boobies", aka a "gluteal orthodic". He then found other sufferers and joined a support group. However, none of that happened since it's just a cartoon show.
There is, however, a real disease called "Gluteal Inflatus Syndrome". Jennifer Lopez is a famous sufferer, and has made a series of PSAs (including ones played during KOTH) attempting to call attention to the issue and raise awareness.