Ear worms (as defined by KFOG) are those songs that get into your head in the morning and are still driving you nuts when you go to bed. Basically anything by Mika falls into this category.
But I had a pleasant one the other day, by a band from the 90’s that no-one remembers now: Londonbeat. The song was called “9am (The Comfort Zone)” and it was just really nice. A nice ear worm.
And now you know the word to describe that tune in your head.