sorry just got around to this thread.
I used to date this Catholic girl many moons ago, when the petting got heavy she would suddenly bite me and almost hard enough to break skin.
But not down" there"we never got that far and I'm not sure I would have let her anyway. I never really understood why she did it, she didn't seem to either.
biting ok ;a knife I don't think so slippage is to much of a risk.
I would feel sorry for a girl with that fetish
Because she would never get to do it.