Expression variants

Hello, I remember I've seen somewhere on this site how to indicate that an expression in the lyrics of a song is a variant of an expression already listed, but I just can't find it again. I saw the French expression "ça ne vaut pas la peine" and I immédiately thought of Beau Dommage's famous song, La Complainte du phoque en Alaska , where it stands under the colloquial form "ça vaut pas la peine". How can I make a link between the song and the expression ? Thanks in advance !