Does anyone know what it means? I found these explanations, which are of no help, since I don't know what "côgne" is. I suspect it might be something like 'hunch'.
côgne (un). Cou de travers ; on dit : cet homme est côgne ; c'est-à-dire, il a le cou de travers,
Côgner, verb., pour avoir le cou de travers ; on dit : tiens donc ta tête droite , tu côgnes, ne donc côgne pas. Context: Robert le diable. Il [the king] fit apporter foin, fourrage et paille, fit installer un lit sous la voût, près des chiens, au malheureux qui tenait son cou de travers.
ETA: okay, I think I should look at it as "il tenait son cou" = "he held his neck" + "de travers" = "awry, crookedly" as Wiktionary says. *sighs*