Yellow and brown are colors that Christopher avoids. If, on the way to school, he sees four yellow cars in a row, he determines that it is a Black Day, and therefore he must be very careful: “I don’t speak to anyone and sit on my own reading books and don’t eat my lunch and Take No Risks” (24). Once, he suffered a second Black Day in a row and sat in a corner, head against the wall, groaning, which helped; nonetheless, on the third day, he rode the bus to school with his eyes closed. A Black Day is distinct from a Good Day.

A Good Day is one in which Christopher sees four red cars in a row. Such a day contains good fortune, and Christopher gives himself a lot of freedom to be happy. Three red cars in a row cause a “Quite Good Day,” and five red cars in a row cause a “Super Good Day” (24). A Good Day is contrasted with a Black Day. Good and Black Days characterize Christopher’s self-made superstitions and help the reader understand the way his mind works.