In junior high school, I was doing dishes (under duress, as usual), and since the batteries to my Walkman had run out again, I was humming to pass the time while my fingers got progressively prunier. After zoning out, I found myself humming a tune that, upon reflection, I couldn't quite place. Where the hell had I heard it? Finally, it came to me. It was from this commercial:
Why that stuck in my head, I can't tell you.