I've heard it in more than one. Two that come to mind are a garden product commercial (like fertilizer or soil or something) I saw in the summertime, and one I just saw the other day advertising some sort of drill thing. I have a theory it's in all the commercials that are talkin' about something specific. I know the music for both of these commercials is the same; if I remember correctly, it's just this really soft, corny acoustic guitar music, and I think there might be some harmonica in it too.