Primarily Greeks represented those whom they thought of as barbaric or uncivilised, or even immoral as having large or even super-large genitalia. Frequently centaurs or cyclops or other mythical creatures were depicted in ancient Greek art with large genitals.
Therefore Greeks, civilised and not barbaric were idealised as having more modest endowments.
I think the evidence suggests they thought that the larger the genitals the more libidinous the man, therefore the more likely to be luxurious and unmanly, and the less likely he would be martial, disciplined, highminded and civically responsible, things the Greeks held dear.
Amidst all the various forms of homosexuality the Greeks recognised and or engaged in there was one stereotype which depicted a feminised and luxurious type of predatory homosexual who is often depicted as having large genitals. This character appears on vases and other vessels and is seen as the opposite outcome in type to that which socially accepted and promoted forms of ancient Greek homosexuality were intended to mould Greek men into.
This was the opposite of the archetypal Eros between men which was expected not to be entirely focused on sex and was supposed to encourage male bonding/or more specifically intimacy and love and encourage bravery and martial and physical superiority.
Though I hate to briefly diverge from the topic of stolen novelty statues of Priapus at the value of $15 (hilarious), I can't resist my nerdy urge to throw myself headlong into this and discuss a point Hilaire made about the accepted forms of Greek homosexuality and talk about those Ancient Greeks and their small penises...
Most of the Greek literature that I've read seems to establish a relationship between all but one 'form' of homosexuality, femininity, and barbarousness. I'm using the term 'barbarousness' quite broadly; the Ancient Greek word for 'barbarians' was synonymous with the word 'foreigners', as both are denoted by the noun οἱ βαρβάροι. So, generally speaking, any person whose native language wasn't Ancient Greek was denoted as both 'barbarian' and 'foreign' in the same word. I think that in his
Histories, Herodotus actually refers to the Persians as 'the barbarians' more frequently than 'the Persians' or whatever. Within Aeschylus, the adjective 'un-Greek' -ἀνελληνόs - is also used to express 'outlandish' or 'foreign'. Essentially, Greek is the language that gave us 'our' word 'xenophobia': ξένοφοβεα. This is where those damn gays come in:
As far as I can tell, there was only really one acceptable 'form' of homosexuality in Ancient/Classical Greece (documented as we know it via red-figure vases and Greek literature) which adhered to quite strict social conventions: παιδεραστία, 'pederasty'. I'm sure most people who have posted in this thread know about the ἐραστής-ἐρώμενος relationship (active older male+passive young man) it but for such a filthy sport it had some surprisingly exacting criteria! An ἐρώμενος is always depicted as a μειράκιον ἀπώγων - a beardless lad - who could (according to the Liddel, Scott & Jones lexicon) range anywhere from the age of 12 to 20, broadly speaking. The older, active man (ἐραστής

is generally depicted in vase painting as a πώγων (bearded male) but I can't imagine this being an absolute. According to Plato in the 'Protagoras', Socrates was still chasing after his young ἐρώμενος, Alcibiades, when Alcibiades himself had a beard that required to be shaven daily (so quite possibly over 20?). The response to this in 'Protagoras' isn't exactly favourable, so I suppose that coming of age/growing a beard changes the relationship from pederastic to homosexual; the latter being unacceptable but the former being something of a tradition among the Athenian elite. Alcibiades was stunningly rich and later went on to be a subject of some controversy; he was accused of defacing holy statues, but worse still, of homosexual (i.e non-pederastic) relations with the members of his political 'gentlemen's club' (ἑταιρία

. As far as I can tell from literature, pederasty was quite common among the highest rungs of Greek society; but obviously finding a source discussing the private life of a 'common' citizen or a slave is like finding a needle in a haystack.
So what I'm now wondering is this: were other forms of homosexuality viewed as unacceptable (as was a relationship between two grown men) by the Greeks on account of being 'foreign' and 'un-Greek'? Pederasty was seemingly an upper-class tradition and respected by the Greek aristocracy, not being devoid of 'Greek' virtues (which the Romans later adopted) that Hilaire identifies: responsibility, martial prowess, discipline, etc. But homosexuality proper? It is said that Alexander the Great (who lived around 100 years later than those dirty pederasts, Socrates and Alcibiades), after his conquest of much of Asia Minor, began to adopt colourful Persian dress and incurred the censure of his
sang froid Greek companions for its lack of masculinity. Feminine, non-Greek, barbaric homosexual garb spoiling a (potentially homosexual) king...and femininity in a man was seen as hateful by both the Greeks and the Romans: in his
Meditations, Marcus Aurelius labours the point of how odious feminine men, and particularly gays, are to him. Maybe some people still share this view.
One scholar has identified, from observing vase-painting alone, that the act of pederastic sex may actually have entailed a sort of frottage by the ἐραστής between the closed thighs of the ἐρώμενος, and involved no penetration whatsoever. Doubtful...

On a final note - which is actually relevant to the thread title - check out the red-figure vase paintings of the Satyrs. I read somewhere that in Greek New Comedy (Aristophanes?) they wore giant wooden penises as stage props, but rather than being revolting or horrifying as Hilaire suggests (as they no doubt were in other contexts), the enormous penises were simply an object of laughable incredulity for comic effect. Interestingly, the satyrs also represented fertility and growth, just like the god Priapus, who was mentioned earlier. Large penises = good as plant feed, but a little barbaric?
I hope I haven't killed this thread; I think I actually managed to bore
myself there...