A counter dibs shield is a defensive word to counter the attack of a counter dib, therefore, canceling out the counter dib.
(The counter dib shield does not have to be explicitly recited as "counter dib shield", it can also be recited as simply "counter dibs" at the same time someone else is calling a counter dib by saying the same thing.)
Fogey/fogy /fougi/ sl. (early 18C+, orig. Scot) old-fashioned, stuck-in-the mud.
Person with old fashioned ideas which he is unwilling to change: Come to the disco and stop being such an old fogey!
You think me an old fogeyand an old tory, his thoughtful voice said. I saw three generations since O’Connel’s time. I remember the famine. Do you know that the orange lodges agitated for repeal of the union twenty years before O’Connel did or before the prelates of your communion denounced him as a demagogue? You fenians forget some things. (James Joyce, Ulysses. PenguinBooks,1992. p. 38)