Warning: The following column should not be read by anyone who doesn't want the theme song from "Gilligan's Island" constantly replayed in his or her head for the remainder of the day. Whoops! Too late! "Earworm" is the word a university professor has coined to describe those irritating songs or jingles that get stuck in your head and drive you so crazy that you'd rather leap off a high building than listen to your brain replay "A Lion Sleeps Tonight" one more time. James Kellaris, a University of Cincinnati marketing professor, has done an intensive study of this subject, leading...