Should have done this last year. jyrddog is, of course, junkyard dog. Originally it was a handle I used in some of my flight simulator games. Then I realized there were two other connections: 1. the Jim Croce tune, 2. reference to my occupation: to wit- I am a teacher with a certification kindergarten through 9th grade or k-9. Of course k-9 or k9 refers to dogs, so I call my certification my dog tags! I also answer to 1. jyd, 2. yard dog, 3. the dog, 4. hey you, 5. dinner's ready!