I never don't have an earworm.
There is always a song playing in my head, and it's usually the last one I heard. The worst is when I don't like the song but can't get rid of it. I never used to notice it, but my husband says I hum all the time. One time we were in the supermarket and I started humming so loud that the guy stocking the shelf near me looked at me. My husband said I was really getting loud. Once in awhile, I catch myself singing, also.
There was a country song some years ago called "Lucky Man." It was stuck in my head and I remember riding the elevator at the mall and all of a sudden realized I was singing "I'm a lucky, lucky man" out loud. lol