The cost of a slice of plain cheeze New York pizza bought at one of the many "walk in off the street and grab a slice" pizza parlors in New York City, has traditionally always seemed to be about the same as the cost of a subway token (now supplanted by the MetroCard), i.e., the cost of a ride on the New York City subway; they've both gone up in price more or less in tandem. There's Wikipedia article about this phenomenon under "The New York Pizza Connection."