It's about the death of Elvis, one of two songs Zevon wrote about Elvis ("Jesus Mentioned" is the other). The song, written with Jorge Calderon, was inspired by a postcard that Calderon had showing the monkey in Elvis's TV room. The song is a cautionary tale of the last days of Elvis. The much earlier "Jesus" was written not long after the death of Elvis and strikes me as a profoundly moving song, though some find Zevon's imagery grotesque. For the record, despite two Elvis songs, Zevon has said that Elvis was not a great influence on him.