When Titus Pullo is in the arena, one of the gladiators taunts him with something like... The 13th are all Mollies'. What are Mollies?

Just a guess, but I would say it would be referring to Molly, a female first name.

No... Rome is quite clever and uses a lot of what I would consider to be old English words, I presume originating from Latin, such as Cak for excrement... And this insult is the one that really snaps Titus' temper. So I am absolutely sure it is very specific, and probably obscene.

Cack is used all the time in england... :)

It means to defecate

Cack-handed, etc.

Possibly came from the latin cacere, but it's a verb.

It certainly isn't clever...

I'm fairly sure that Molly would be from the female name and would indicate something feminine. Or the other thing it is used for in England is sometime school children use it to tease other children who look like their mothers have dressed them.

In any case, it isn't a very latin-sounding word.

I'm still convinced it is something more 'powerful'. I can't imagine the equivalent of calling Titus Pullo 'A big girls blouse' having the effect that it was supposed to have.

I like finding Latin words being used in a modern context. I think my favourites are scrotum, which I understand is purse and cloaca, which is bum of an animal with only 1 multipurpose orifice such as a hen, which is Latin for sewer

The gladiator was calling the men of the thirteenth "queer".

Here is a quote from a web article (emphasis added) :

But the fact of the matter is that a great many indigenous societies did have words for 'the homosexual'. By this I mean that they had words which identified a homosexual personality type, not matching the sexological psychopathological personality disorder (which, baldly stated thus, undoubtedly is a modern social construct), but words roughly equivalent to modern queers – words which demonstrate a consciousness (albeit often contemptuous) of a queer stereotype or gay identity. Here are just a few words for queers from many hundreds: in the Middle East the xanitha plays the receptive role with older or richer men; in Nicaragua el cochon; in Italy the arruso and ricchione, and femmenella, little female, for the transvestite; Loca and maricón in Latin America; the teresita in Argentina; bicha and veado in Brazil; masisi in Haiti; zamel in North Africa. In many languages the generic term for a male homosexual is derived from a female name: Spanish maricón and mariquita derive from María; Italian checca derives from Francesca; Flemish janet derives from French Jeannette; a Portuguese queer is an Adelaida; in England queer men have called themselves Marys, Mary-Annes, mollies, nancy boys, nellies.

Here is the link to the actual web article itself:

Passive Roles (http://www.infopt.demon.co.uk/social09.htm)

Exactly, it's been used in England in this way for ages.