My earworm today is some death metal lyrics I wrote earlier...'Come with me he says through the valley and into the pines/Or I will cut off the head of the Red One who guards the Spine'.
Doesn't have a melody by itself, but the guitar riff for it took some working out and then I ended up obsessively playing it in my head.
It's...a bit of a dark song about someone in an unhealthy relationship. I don't think you want me to explain who the 'Red One' is.