The headword phrase is Aristophanes, Frogs 964-5 (web address 1); again at mu 395. Euripides is speaking, and referring to Aeschylus; he goes on to name his own pupils as Kleitophon and Theramenes.
The gloss (from the scholia to the line) appears to assume the correctness of the reading Manes rather than Magnes ("from Magnesia") at the end of 965; modern editors (e.g. K.J. Dover) print it anyway, and observe that Manes is a stock comic name for a slave. Beyond that, though, the comment of the scholiast loses its plausibility, as regards both Megainetos - the actual name of "Manes" - and Phormisios. Appreciation of the joke here would be easier if all four individuals (Phormisios, Megainetos, Kleitophon, Theramenes) were securely identifiable; nevertheless, as three of them were prominent anti-democracy figures of the day (Phormisios, Kleitophon, Theramenes: ?Aristotle, Athenaion Politeia 34.3), there seem good grounds for thinking that all four were.
cf. mu 394, mu 395, phi 605, phi 606.