The title refers to a gimmick used by Kmart stores in the 1960s. It faded away, then was resurrected in some stores.I don't know the current status of the blue lights or Kmart stores themselves.

A flashing blue light would be wheeled around the store and when it stopped, an excited announcer would say something like, "Attention Kmart Shoppers! We have a Blue Light special in Ladies' Hosiery for a discount on 3-packs of tummy control panty hose! Assorted colors, sizes X-small to 5X. The first 10 people to arrive will get 40% off, so HURRY!" It was loudly mocked by smart-alecks in the store (like teenage boys), adding to the fun.

Example: tinyurl.com/r5b5qme