What does »fiß, biste patzt» mean?

Question

In Walter Kempowski's novel Uns geht's ja noch gold I came upon the phrase »Fiß biste patzt«. Context (emphasis mine):

Oder Gemüsepaste. Fiß biste patzt. Die frequentierte man nicht so gern.

Google books search yields a few more results. It appears most if not all are from Kempowski:

"Nein, es gab Nudelauflauf mit Kartoffelings, wie ihn mein Vater so gerne aß. »Malsoweit«, hieß es, und: »Fiß, biste patzt.«

(from Tadellöser und Wolff, Walter Kempowski)

A non-Kempowski usage comes from this forum post:

Ohja... Schoki :-) Lecker! Iss man ruhig - meine Oma sagte früher immer zu mit [sic] "fiss biste patzt"

Or the title of this weblog. However, it's possible that Kempowski invented this and that both are quoting Kemposki.

What does »fiß, biste patzt» mean? How do I parse it? I think it's in a northern German dialect, possible Rostock dialect. It's clearly related to food, and perhaps not particularly positive.

Wiktionary has no entry for fiß or fiss. It lists biste as northern German dialect for bist du, and lists two meanings for patzen; firstly einen nicht so gravierenden Fehler (Patzer) begehen; the second meaning is Bavarian which would an unlikely fit, this being in Rostock. Those meanings do not make sense to me in the context of commenting on food.

Answer 1

I do not know the original work, however, I would propose another explanation for the peculiar spelling of the phrase

Fiss biste patzt! <--[derived from]-- Friss bis du platzt!

That's not at all a dialectal pronunciation. It is, quite conceivably, the pronunciation that would happen if you stuffed your mouth with food and then tried to utter that sentence, as with a full mouth you have a hard time pronouncing r or l.

As good writers don't write things just so but do it with a reason, I am sure this is a deliberate mise-en-scène of a voracious person speaking.

You could go to the extreme with this, i.e. imagining a person with a totally fully stuffed mouth. This person would then probably be heared saying something like:

Fiff biffe papf!

But I suppose Kempowski found this too much, and also a bit too difficult to trace back to the intendend meaning.

Answer 2

Scheint ein Dialekt oder Jargon zu sein.

Friss bis Du platzt.

Also iss wie ein Tier, bis Du platzt.

Friss schrieb man bis vor ca. 20 Jahren noch Friß.