Est totus graecus mihi.
Now you really said, “He’s all my Greek,” which neither strikes me as here nor there—so just get down, girl! But if only to demonstrate how your quaint Latin excercise might also have very pressing need of some canine etiquette, “it’s all Greek to me” could perhaps be more literally rendered tota sunt nobis Graeca in any formal, classroom setting:
tota = natural gender to agree with understood haec neuter plural for either spoken or written speech and usually glossed with singular “this” in our proper idiom.
sunt = logical copula inserted here between two adjectives modifying each other tota & Graeca but thanks rather to syntactic eloquence, than to correct word order.
nobis = dative plural yet with copulative verb quod cf. supra preferred by much over sing. number mihi for editorial reasons of good Latin prose, “It’s all Greek to me!”
Graeca = standard adjective used for that classical allonym Graecum which has moreover as its Greek autonym Ἑλληνική “Greek language” only to rephrase said Latin expression with a less familiar adverb tota Graece “all in Greek” and, by no possible means whatsoever, err to say diminutive graeculus “queer bastard”!
