My mother and I were watching a documentary on Richard III and how his skeletal system was showing a variety of wounds, all seemingly caused by weapons, etc., etc.
And his skeletal system showed a wound like... where... his butt would have been. Specifically a lower buttock cheek.
And Mum was like, "Maybe it was considered an insult to stab guys in the ass."
THUS MY INAPPROPRIATE QUESTION TO GOOGLE BEGAN.
To which my mother said, "I bet Google looks at questions like that with 'what the fuck' written all over their faces."
I was unable to find anything on it. I'm inclined to say that my mother was incorrect.
Stabbing someone in the butt was not an insult at that time, but could very well be now.