Where does the idiom/story "You know what happened to the man who forced his pig" come from?

This phrase comes from my dad, who is of Bristolian stock, so it may be highly regional. I've only heard it spoken, and not written down.

He uses it, I believe, when it looks like somebody is straining to accomplish something, and taking a more relaxed approach would be better for all involved. The exchange usually goes something like this:

Dad: You know what happened to the man who forced his pig, don't you?
blank faces and/or groans
Dad: Died.

I think the humour comes from the ambiguity over whether the man or the pig died, and what the pig was forced to do. That ambiguity also covers the fact that this strenuous activity is probably bad for the man AND the pig, no matter what it was.

Have I got the meaning right, and where does this actually come from? My dad doesn't know, but he's sure he didn't make it up. I've also seen the phrase/expression mentioned elsewhere but I've not found any answers as to its meaning and origin.

Examples in Google Books:

It was times like these that I'd decide it was time to visit Nanny. “A man forced his pig and it died,” she'd often say without elaboration, once I'd settle into her musty, lemon sofa beside a bowl of calcified fruit drops. I never knew what she was talking about. Jeff Wells; Anxious Gravity

JANET Give it up for the time being. Don't try forcing it. A man forced his pig and it died.

HOWARD Forced it to do what?

JANET I don't know. That's what they used to say. Anthony Burgess; One Hand Clapping, adapted for the stage by Lucia Cox

The pigs’ stubbornness extends even beyond its own best interests. Obstacles or change be damned. Pigs prefer to move in a straight line with a single-minded purpose that resists deviation. Pigs have their own inertia and an internal frame of reference. Dano; "The stubbornness of pigs"

pigheaded (adj.) Obstinate and stupid

Someone who's extremely stubborn, refusing to change their mind even when it's in their best interest, is pigheaded. It's almost impossible to get a pigheaded person to listen to your advice. vocabulary.com

It appears that the expression intentionally omits what the pig was forced to do: being such a stubborn animal, it doesn't matter. I think the gist of the expression is "don't push it" or "insisting will have consequences" as you suggest.