The Romans didn’t necessarily draw the distinction between serious and comic that you’re drawing - the possibly-related Fescennine Verses, for instance, were both ribald and profane and intended to ward off ill luck.
As for the mediaeval examples, one theory is they’re related to Carnival culture, and that others are mockeries of specific normal pilgrim badges (e.g. one depicting a ship of dicks being in imitation of the Thomas-Beckett-on-a-ship badge)
Good point.
Underlining mine.
I was mightily confused for a couple words there whether “she” was your sister or your sister’s dog. Then it became obvious. Pronouns are dangerous shotguns.
Naw, I’m good. 
But it was my sister’s dog who was eating the rawhide, not my sister, in case anyone is more confused than amused.
Reminds me of this extremely NSFW and hilarious moment in Silicon Valley.
Best response: “Sure, if I can find it. Got a magnifying glass?”
You’re not the only one with that opinion (google Armin Miewes; I won’t link here).
And “scumbag” apparently refers to a condom (specifically a USED one, I think). I was well into adulthood before I heard that connection.
Weirdly, despite my somewhat well-known potty mouth, I try to avoid those two terms.
Just wanted to say that this topic was in my unread list right before “how do I stop eating so much?” Which makes for a funny two-part question.
In cockney rhyming slang Richards = shit.
So it works either way.
It does, quite well. “Richard [the Third]” means shit in the specific sense of the countable noun “turd”. So it’s either a satchel of dicks or a satchel of turds.
For a British person, there is nothing wrong with having a nice serving of spotted dick for desert.