Jayto, I think there are two different but related phenomena -- one is that dang tune that gets in your head and plays for days (and it can just be a rhyme like "tenser said the the tensor") and then then other related phenomenon is that our subconscious has a top forty that it plays for us -- a lot of us, anyway -- and if you pull up the background noise you will find that it tells you something about your current state of mind.
At least I hope so, because I was stuck with Little Gomez for about a week after I heard it on an Eric Bogle recording... a thoroughly irritating melody, and the words, well, gak, they're about a chihuahua in rut...
On the other hand, my subconscious routinely plays me "you don't know, you don't know, you don't know my mind..."
Blessings,
Barbara