When I first heard this, I thought it was a joke. But it's really Willie Nelson, and the song is available at iTunes. Apparently a friend (a cowboy) admitted this to Willie, and he recorded the song in honor of his friend.
http://my.ev1.net/english/news/newsarticle.asp?articleID=50156717&subject=entertainment
http://my.ev1.net/english/news/newsarticle.asp?articleID=50156717&subject=entertainment