I'm a whistler by default. And by that I mean that I whistle a LOT! Without really being conscious of it. Today as I was tooling my way up a long dirt driveway I was whistling fairly loudly I guess, because when I got to the woman's house she said, "I could hear you whistling all the way up my road. What a lovely song that was. What was it?" I, of course, was kind of embarrassed having not known I was being listened to and not really even knowing I was whistling said, "Uh, I don't really know." "Well, whatever it was" she said, "keep it up."
Two hours later as I was making the hour drive back to my building I realized I was doing it again...whistling by default. It was the same song I had stuck in my head all day. Who knows why? I surely don't, but I do know it's one of the best songs I've ever heard and it always reminds me of summer.