Kmart, formerly Kmart Corporation, is a department store chain and online retailer in the United States and its territories. The Blue Light Special was a sale promotion within the store for a short period within store hours only. It was advertised using a rotating blue light, in the same style a police car used, and was announced over the store public address system with the phrase "attention, Kmart shoppers", a phrase which became a pop culture reference.

Source: Wikipedia