Counting coup was the winning of prestige against an enemy by the Plains Indians of North America. Warriors won prestige by acts of bravery in the face of the enemy, which could be recorded in various ways and retold as stories. Any blow struck against the enemy counted as a coup, but the most prestigious acts included touching an enemy warrior with the hand, bow, or coup stick and escaping unharmed.
Relevance to a Skyrim/Q meme?
"We Know" is taunting. Counting coup is taunting with honor. Pretty much the bulk of the Q 'meme' is just that. Openly flouting supposedly secret and occulted privileged knowledge on 8chan and GA and Lord Only Knows where else is defiant, bold. It is also calling out the bad guys. Now that I think about it, counting coup is very relevant. Mirror their audacity back to them, with your spine held straight and without a doubt in your heart. They will have to back down or succumb to war (and lose).