Webcomic Deer Rectory

I was actually pretty sure it was a book code after seeing them each say one pair of skulls last comic, and going off of Supe's incredulity about knowing what book to use I thought it might possibly be Paranatural itself, but I didn't go check. Wish I had!

Edit: Not sure I would have figured out the skull -> number scheme, though.

Edit2: Does this mean the "foul crime" you have to commit to learn skull language is reading Paranatural?