Brain Sludge, by the infrangible Bill Roper. And he looks like such a nice man, too! (I’d point to the lyrics, but Bill hasn’t posted them anywhere.)

And let me give a shout to Filk Radio while I’m at it. Especially made for those who like their music on wry. (If you have iTunes, you don’t need their dedicated player, but you won’t get the song titles if you don’t.)