What does “three inches of plate in my skull” mean? I tried to google it, but it seems it's not a set expression.
“According to my archive I was constantly in some fight or another over email. I apparently have three inches of plate in my skull. And in fact, because I believed, and have believed for so long, that I once was passive but am no longer, I think I tend to be even more likely to be passive-aggressively aggrieved than the typical person.”