A foreshadowing in the book "Tuck everlasting" is; the fact the when the man in the yellow suit shows up that he is in a "YELLOW suit!" Because, usually the color yellow is usually symbolized as a warning the man in the yellow suit is, when first presented, a broad "watch out! Trouble in the near future" sign. It foreshadows that he is an enemy and the fact that he is going to be a source of danger soon!