I don't know if this is really in the dictionary or something but it means having a song playing in your mind. This usually happens when you keep on listening to a song often and then even though you are not anymore listening to the song you still...
there are times that we feel so down and we cant help it... we want to be alone and we unwind ourself... we often sleep or watch t.v. and listen to music others play and enjoy their self as their defense mechanism...for me i usually listen to...