And a ham!
First of all: the picture on the right is a ham; this is not a ham. This very Spanish expression means that you are firmly opposing another person’s proposal; it’s the equivalent of the English “no way!” or “yeah, right!” We could say it’s now old-fashioned, since it’s being replaced by other similar expressions, more vulgar, namely ¡y una mierda! ‘and a shit!’, etc. However, it will always be remembered for its appearance in classic Spanish comics such as Mortadelo y Filemón.
We have three points to comment about in the Latin translation: the exclamative accusative, the word perna, ‑ae itself and the choice of ‑que as “copulative” conjunction.
According to grammars, nominative (and vocative) and accusative can perform this exclamative function; accusative, they say, is the most common case for this function, so we shouldn’t be wrong with it.
As for the word pernam, obvious mother to Spanish pierna ‘leg’, in Latin it referred to the legs of animals in general and to edible animal legs in particular, that is, the hams. This is a good example of change of meaning between classical Latin and vulgar Latin and the results in the Romance languages. Despite the reasonable resemblance, English “ham” doesn’t seem to be cognate with jamón; instead, jamón comes from French jambon, from jambe ‘leg’ (from Latin gamba ‘hoof’) with the diminutive suffix ‑on.
The choice of ‑que as our copulative conjunction lies in what grammars say, that ‑que is the most archaic form and, since the Spanish expression is already old-fashioned, ‑que suited it; anyway, I have to admit that it’s also because it’s what I thought was funnier.
So now you know how to rebel in Hispania: pernamque!