SINGER-SONGWRITER, 70, BLOOMINGTON, INDIANA __ I AM THE luckiest motherfucker in the world. __ I WAS BORN with spina bifida. I had my head cut off when I was six weeks old. There were three other kids who had that same operation that day. The other kids died, and I lived. One girl made it for a while, and I used to see her at basketball games. She was paralyzed from the neck down. She died when she was about, I don’t know, thirteen. __ WHEN I FIRST got the name John Cougar, I said, “No, no…