TRISSIE: https://www.pourquois.com/expressions_langage/pourquoi-avoir-cul-borde-nouilles-.html

To have the ass bordered of noodles means to be lucky. This expression would have originated in Marseille around the 30's when people were talking about Italians who are big consumers of pasta.


In this corner of the south where many phrases are exaggerated, people said of a lucky person that he or she had an "ass". The Marseillais, as they went along, would have added for the lucky Italians, the noodles at the end of the sentence.


Other more or less tasteful suppositions are also put forward. The Germans, who have a more polite language, say for this expression "to be the mushroom of happiness".

Complement internaut :
At the origin of this expression, there are the people of the West, who say of a lucky person that he has the "smell of good fortune". The Italians would then have added the ''noodle''. Finally, the Germans would have added "le champignon". The French are not the only ones to have this kind of term. Cul de canard'' or ''cul-de-sac'' means luck, while ''cul de l'air de'' means money. People in London say the same way as people in the south, that they are lucky to have cabbages in the garden.

Translated with www.DeepL.com/Translator (free version)

TRISSIE: já to třeba nevěděl .o) spojení mít prdel plnou nudlí jsem tedy v životě neslyšel

NJAL: Zvyk je železná košile. Si vem, kolik lidí mluví o Fučíkárně a podobně, ač se to tak dávno nejmenuje. A proč měnit pojmenování stran jen proto, že se nedávno kormidlo přesunulo doprostřed? :)))