Literal translation
in Aubagne, when it rains, one gets wet
Meaning
in Aubagne, when it rains, you get wet (a mock statement of the obvious)
Explanation
This expression states an absolute obvious truth in the form of a fake local saying, poking fun at pointless remarks or claims that teach nothing. À-n-Aubagno (in Aubagne, with the traditional euphonic n before a place name starting with a vowel) sets the statement in this town of the Bouches-du-Rhône, but the truth announced, quand plòu si bagno (when it rains, one gets wet, from bagna, to wet, related to bagno, prison hulk), would hold equally well anywhere else : nothing specific to Aubagne explains why one gets wet there in the rain. It is precisely this lack of specificity that gives the expression its point : it mimics the form of a local saying, supposedly revealing a distinctive trait of a place or its people, while actually stating nothing more than a truism. The register is light and ironic, used to good-humouredly mock an obvious remark presented as if it were worth noting, or more broadly to poke fun at the very genre of the local saying when it collapses into pure banality.