Metal Gear Solid 2 (Playstation 2) Easter Egg - Happy Birthday to Guards

First load a save after you have completed the game and where you have most/all dog tags acquired, or use the Gameshark code. Make note of each guard's birth date. Now try to find him. When you do, and use the Camera/Digital Camera/Scope to view his tags (press triangle), a Happy Birthday!! message will be displayed in green just above his name.