The headword phrase, an iambic trimeter, is Aristophanes fr. 902 Kock (902a Edmonds), now 928 K.-A.
[1] Xerxes' invasion, evidently.
[2] The rare adjective dusei/sbolos, 'hard to penetrate', is normally used of landscapes that are hard to invade or to travel in. Here, awkwardly or perhaps inventively, it is applied to the voyage by sea (plou=s) to a place. A literal rendering is retained, as there is surely a sexual play on words. (Incidentally, the juxtaposition of the adjectives dusei/sbolos and xalepo/s occurs also at Aeneas Tacticus 16.17 with reference to an imaginary polis territory, and at Strabo 5.1.5 with reference to Egypt.) For Corinth as a place of courtesans et al. cf. chi 601.
[3] This material occurs several times in late antique literature. It is entry omicron39 in Pausanias the Atticist (2nd cent. AD), Attikon onomaton synagoge (Collection of Attic Names), ed. Erbse; it is reproduced by Photius (9th cent.), Lexicon omicron667 Theodoridis; and it reappears, post-Suda, in Apostolius (15th cent.), Collectio paroemiarum 13.60. For different lines of interpretation see e.g. Zenobius 5.37 and Hesychius omicron1799 (5th/6th cent.): "'not every man's lot (is) the voyage into Corinth': (thus) Aristophanes, since to foreigners sailing into Corinth the city seems rather difficult (xaleph\) because of the bewitching charm (gohtei/an) of the courtesans. For the Corinthians were enthusiasts for this, and lived a life of idleness (r(a|qu/mws dih=gon) for this reason." See generally Tosi [cited under alpha 378] no.1551.