I was reading a book of Tom Waits interviews the other day when I saw that he did the voice of Tommy the Cat on the eponymous song by Primus. Looked it up on the credits. TW's there, as "voices."
A P.S. of Duh.
Tommy the Cat. O-kay. It took a while, but I put it together. Tom Waits. Tommy the Cat. How often is it you get to sing on your own hommage song?