κάγ
From LSJ
τὸ ἐμόν γ' ἐμοὶ λέγεις ὄναρ → you are telling me what I know already, you are telling me my own dream
English (LSJ)
poet. form for κατά before γ, κὰγ γόνυ for κατὰ γόνυ, Il.20.458;
A κὰγ γόνων Sapph.44; κὰγ γᾶν dub. in SIG179.9 (Boeot., iv B.C.).
Greek (Liddell-Scott)
κάγ: σπάνιον ποιητ. τύπος ἀντὶ τοῦ κατὰ πρὸ τοῦ γ, κὰγ γόνυ ἀντὶ κατὰ γόνυ· κὰγ γόνυ δουρὶ βαλὼν Ἰλ. Υ. 458· κὰγ γόνων Σαπφὼ 25 (50).