JB, yes "cul" is st. French (maybe also in some parts of Louisiana (?), but most of the time it's "tchu" in Cajun French).
"Embrasse mon cul", as an insult, does not exist in France. Its equivalent is "va chier" (literally "go s h i t"). Both are located in the same region.
But I suppose it is perfectly understood by Louisiana French speakers since it's the literal translation of an English expression.
the real way to say that cajun is Bec mon chu or an equivalent and favorite of my grandfather mange la *****. I have never, ever heard embrasse mon cul. that sounds like something a tourist would say
I'm sure it varies widely by region, but I would guess than any form of "kiss my a s s" would be an Americanism in French. The main one I remember hearing to be used in this circumstance was "va la m e r d e, tcheu".
Amanda Lafleur's book "Tonnere Mes Chiens" has a lot fo these sayings, one for every occasion.
Ah, family business? PS i wonder what JLM would say on this whole caboose; if he turned lurker his typing fingers must be slightly itching by now .... - Nout