"The Hi Fi Show." Each night, the DJ would explain how to acquire the card, usually a trip to the KTEL studio "high atop the Book Nook Building". Native Walla Wallan Jaynie Jones, who carved out an outstanding radio career in Seattle provided this.
When I got my card, in the early 70s, it had a number. Eventually the station vacated the Book Nook and moved their offices and studio to the transmitter site at 2nd and Tieton.