The phenomenon of pop songs coming to mind and then playing in your head, sometimes for hours on end.
Particularly common of terrible pop songs you couldn't stand to listen to when you were 12 but somehow retained all the words and chord progressions to anyway.
If I can't get Hall & Oates off my head radio, I'm going to shoot myself.
Term used for when you have a ton of songs floating through your head.
Girl: what the heck is she singing to?
Brother:Oh, shes just singing to her head radio.