(it's) (all) Greek to me
This might as well be a foreign language, because I don't understand it at all. The phrase comes from Shakespeare's play Julius Caesar. Can you make sense of these instructions? It's all Greek to me!
Greek to me
Unintelligible, as in “I didn't understand a word he said—it was all Greek to me.” Shakespeare said it best in this exchange from Julius Caesar: Cassius: Did Cicero say any thing? Casca: Aye, he spoke Greek. Cassius: To what effect? Casca: Nay, an' I tell you that, I'll ne'er look you i' the face again: but those that understood him smiled at one another and shook their heads; but, for mine own part, it was Greek to me.