Jack of Dover
A stockfish, “hake salted and dried.” The Latin for a hake is merlucius, and lucius is a jack or pike. Mer, of course, means the sea, and Dover, the chief Clinque Port, is used as a synonym. Also refuse wine collected into a bottle and sold for fresh wine. “To do-over again.” (See Dover.)
Many a Jack of Dover hastow sold That hath been twyes hot and twyes cold.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894