It has happened to me when I was extremely tired, sleepy, fatigued all at the same time. I was on a 50 mile backpack trip carrying a 60 pound pack. We had been walking all day, but the last leg of the hike I was so tired I started hallucinating and half-sleeping. I felt like I was dreaming, I didn't feel any pain, and if I looked in one spot for a long time it would start to morf change shapes and everything around it would blur. I kept pinching myself to see if I was dreaming. O yeah, I didn't really care about anything. I tried to think about sex but I just didn't care.

Btw: Is your avatar from the "Bizarro" comics?