Okay, I can't help myself...
On penis size, yes, there are variations with ethnic decent, and being in America REALLY adds variety, but regardless, ALL factors generally fall along a bell-curve. So, it's going to vary regarding to study, but the ones that I've read place spot-on middle-of-the-road "average" as being between 5.25" and 6" (I can't remember the numbers for girth, and not all studies look at that). So, at 6", your "friend" is on the long side of average. And remember, because it's a bell-curve, 6" compared to 5.25" might be a range that accounts for 60%-80% of the players, even if it were only 20% of the playing field. But that's just numbers...
"Hung?" That's a subjective term. What does length, girth, and volume have to do with "Hung?" In fact, I'd hope that a man is only hanging when he's flaccid. While there's a huge variation in the rarely measured factor of Angle of Erection, and this factor is NOT really a factor in "performance", it does impact visual appeal (I mean, there's a reason we call it an "erection"). And then, when it actually IS hanging, flaccid, there's such a HUGE variation in size (a gentle, sloping curve), with much less relation to the size of the erect member (some increase in size over 300%, and others less then 10%). This bullet-point could be a long one, but to make it short, I, personally, don't associate mere length and girth to be the sole defining factors in someone's having the status of being "Hung."
But, as a sub-point, I read a study discussing a possible reason for that flaccid-vs-erect size variance. Most everybody knows that traditional bicycle seats cause ED (i.e., impotence), and newer studies confirm that it's not so much a question of "If", but "When", and "How Bad?", because of the damage to nerves and blood-flow (and sorry, those seats with the cut-outs, and the gel actually make it WORSE, not better; snub-nosed seats are the way to go). It's like smoking and lung cancer: if something else doesn't kill you first, you WILL get lung cancer from smoking tobacco. And on the subject of smoking, it ALSO contributes to impotence, because of the damage to the circulatory system (reduces penile blood-flow, reducing erectile ability). So, a recent study indicated that there may be a relation between a man's "Grower" or "Shower" status, and the efficiency of his genital circulatory system. So, if you took two men with comparable erect members, but with a significant difference in the size of flaccid members, the difference could be caused by their circulatory efficiency. Essentially, the "Grower's" circulation is doing a spot-on job, moving the blood out of the genitals when not needed for an erection, or heat dissipation, etc., whereas the "Shower's" flaccid penis flopping about might indicate that his circulation is not so good, sluggish, in fact, because it just never manages to move that pooled blood out when not in active use. Now, of COURSE there will be variances, but were talking about population statistics here, so finding a few good men (and a hard man is always good to find) who smoke, ride bicycles, and mammoth (wooly?) trunks swaying to-and-fro that are even more impressive trumpeters does not mean that this theory is incorrect, by any means.
Wow, that was some "sub-point", wasn't it?
So, now that that's all out of the way... "Hung." It's an evocative term, certainly, and one both subjective and aesthetic. Some previous replies have mentioned horses, and certainly terms like "donkey" and "mule" have also been used to describe the so-called "well endowed." But, even taking a particular, subjective bias in regards to size and turgidity into account, could it truly be said that all men of the same proportions are therefore equally well "Hung?" Let's consider the aesthetic. Does it "dangle", or does it "swing", or does it "sway". Or is it mounted in that awkward, poky-outy way? Certainly, non-phalic genitalia play a part in this, like "low hangers" and the like, that may or may not be in any particular proportion to the member in question itself.
And then, all of THOSE considerations dually considered, let's make a further consideration in regards to form. People mention "girth", as being even more important then "length." But just like length isn't always in a straight line, girth isn't always in a perfect circle. There are those of the the ovoid and ellipse persuasion, walking among us even as we speak. But I say to you, the man with the 6" perfect circle of girth, and the 5" in in a distinct oval shape will have very different characteristics. And the shape and set of the glans. The relative looseness of the skin and/or foreskin, to the quality, distribution, and grooming of hair.
I'm not even going to DISCUSS proper usage, mechanics, style, and such. We're so fixated on sticking it in, getting it off, and then what? Was procreation your objective? Is emulating that model the only thing there is? I can tell you that MY objective has a different focus, but don't think I don't have a good understanding of the factors involved (and I'd doubt that more then a very few men even know WHAT all four female genital-erogenous zones are, let alone WHERE; anterior-fornix, anyone?).
And then, there are the women themselves, if we're taking them into consideration. They vary as well, both in terms of actual proportions, and potential ones. There's a reason the ancient vedics had "divine" guidance, with widely disseminated advice regarding the suitability of various men and women for each other, based on relative size. From my own experience, dealing with men alone, I prefer an arrangement that let's us both get in on the action, and doesn't predetermine a restricted set of activities. Axiom: If it makes me bleed out my ass, then it was too big. Consequently, there is a quickly diminishing return on the sexyness-value of increased phallic proportions. I wouldn't REJECT a man for being of unsuitable size, large or small, but neither would I make any attempt for a specimen of large-then-average stock, because, while there certainly are SOME benefits, I don't want to have to go to super-bottom anal stretching classes, or endure that kind of pain during sex (I'm not a physical pain wimp-out; seriously, I practice Aikido (joint-locks, stimulation techniques, and break-falls) and Capoeira (the most grueling workouts known to man, acrobatics, and always, the risk of a sudden take-down, or worse, a kick to the face that you just didn't manage to get out of the way of), but I just don't think that painful-in-the-butt sex is sexy at all), or worse, have that kind of disparity in an intimate relationship, where sexual roles are proscribed by physical capabilities.
Hmm... I'm rambling again. Well, to close, I suppose I shall just say that, in the end, a dick is a dick, and a cunt is a cunt, regardless of the proportions of their namesakes. So, I would say that BOTH parties involved in our tale of the hapless "friend" are out of line, and need to readjust their approaches...