blanc-bec

greenhorn

“J'étais fini, foutu, échec / Et mat aux yeux d’Marilou / Qui m’traitait comme un blanc-bec” — I was finished, screwed, checkmated / In the eyes of Marilou / Who treated me like a greenhorn

From blanc + bec. Literally, “white mouth”, where bec (“beak”) informally means “mouth” (likewise in English slang, which see beak), either referring to the observation or belief that very young birds's beaks were white or referring to the area around the mouth of a White, beardless, young man, which has the white skin visible, not yet covered by a beard and mustache.