It's not a song, but I've always loved the Steve Jackson Games edition of the Principia Discordia... "Copywrite K, All rights Reversed"... Later, he goes on in his intro to encourage everyone to take the book, revise, republish, reissue or whatever the main body of the book... As he put it, more or less, "I did it 'cause I wanted to, and think that you should to".

m