...its more like... if you observe male teenagers (on earth

)...
Well, it's worth pointing out that in the UK at least, it's not just a "male" activity; youths of both sexes drink for entertainment

. Of course, Cardassian society is heavily gendered, so it's possible- likely even- that drinking would be a specifically male thing to them. The show suggested, and the books made explicit, that Cardassian females are expected to advertise themselves as potential mothers, and be "respectable". More "refined", and more restricted in their activities. So I guess it makes sense that Cardassians might frown on young women drinking...if doing so in a non-formal setting is considered at least somewhat uncouth in their culture.
That said, given the regularity with which Cardassian officers and soldiers drink kanar, I'm assuming casual for-your-own-gratification drinking (not just drinking at formal occasions) is an acceptable activity, for males at least. I recall Daro ordering kanar from Ten Forward in "The Wounded". He's on the
Enterprise as part of an official escort for Gul Macet, and he certainly doesn't seem the type to do anything unseemly, so I'm assuming Cardassians wouldn't blink at his having a quick pint when not directly on duty.
As for drinking more than a quick respectable pint...the soldiers on Terok Nor drink a lot, as you say, which might suggest drinking in groups, heavily, is a regular part of their culture. Then again, those soldiers also play very loose with their sexuality. Again, that's presumably far more acceptable for a male in Cardassian culture than a female, but still, given Garak's comments to Dukat ("you, a married man!"), it also seems that they're being
somewhat deviant even with the double standard taken into account. So their drinking might not be considered "acceptable" back on Prime, either...
And then for
youths to drink...hmm, well, in "A Stitch in Time", the youths we meet are enrolled at an official academy for state intelligence, and of course aren't really allowed to do anything for individual gratification, because they aren't allowed to operate
as individuals. Instead, they're part of a group, a piece in the functioning whole. So, no drinking for yourself, certainly. A group activity...almost certainly too undisciplined. Alcohol is likely a big no-no, I'd guess. Of course, these youths are exceptional- those teenagers training elsewhere or in other fields will probably have more freedom. In the business or art institutes, I doubt their private lives are anywhere near as regulated, even if their work is.
I suppose it depends on how tolerant mainstream society is of youths engaging in personal gratification disassociated from service. Probably not too tolerant; the books reinforce the idea that the struggle for survival has hardened the Cardassian culture to the point where free time is almost an unseemly concept. Laziness, they'd call it. Better your family, your Union, don't waste your time with games. That's a
Bajoran thing, that is. (Though the degree to which they take that attitude to extremes varies from book to book. In "Terok Nor", one Cardassian finds the entire concept of play- even for the very young- alien, yet in "A Stitch in Time", Tain mentions children playing in parks. Maybe it differs from community to community?). I'm guessing it's quite frowned upon to indulge in any sort of non-useful activity, though. That's why soldiers on shore leave go so overboard, I guess. They're finally able to let off steam after so much repression back home, where they have to act in a respectable fashion.
So, I'd guess any activity not part of a lesson or self-improvement is frowned on. Logic puzzles and
kotra are fine, as is martial arts and physical training. But drinking...probably not. There might well be rebels- these are teenagers we're talking about- but I doubt rebel youths are tolerated very much. If Cardassians surrender a molar to the judiciary institution at age 10, does that mean the age of criminal responsibility in the Union is 10? A teen who didn't conform might well end up getting subtle threats to buck his/her ideas up, no doubt wrapped in gentle appeals to "do the right thing for your Union". Individual acts of rebellion are probably put a stop to, stamped out.
On Earth, as a teenager, you disrespect the school system. On Cardassia, the school system disrespects
you.
So, I'd guess if they aren't on a border outpost somewhere, then a group of Cardassian youths would probably not be playing drinking games.
...I am reading a book about a soldier, for trying to get somehow in the feeling how a soldier feels like, how military feels like...so I try to bring the male perspective (teen and adult) the only male group dynamics, the military and the cardassian culture together in my head...but I find it very hard.
TerokNor
Just to say, that's what I find great about all this; exploring cultures and sub-cultures and social groupings of all descriptions, including those you aren't familiar with.

It's one of the aspects of both reality and science fiction I find very appealing- and the science fiction element is also of great use in reality.
As for the soldier dynamics, do you have any relatives in the military you could ask? Maybe older ones who
used to be in the military especially, where the "all male" aspect would likely be in place?
Also, I don't know if everyone would agree with me here, but I'd say a large part of masculine or feminine behaviours is in making yourself attractive to the other gender- so I'd assume the young men in question would be somewhat more overt in their displays of their culture's masculinity when in a
non-male only setting. Regulation of your peers definitely plays a large part in it, but I'd assume if you're a man in a traditionally male role surrounded only by other men...well, there's not too much need to affirm or display your masculinity, because it's obvious in that setting, and less necessary that you make a point of it. I'd guess it would be a lot more subdued, at least.
I suppose what I'm saying is, a "young male group dynamic" might differ depending on whether there are females around (the youths would want to attract/impress them), or other, rival male groups (they'd want to intimidate/impress them), or elder males (they'd want to gain their approval/prove yourself/impress). If it's "nothing here but us young males", then there might be a bit (okay, often more than a bit) of group regulation and judgement, but there's less desire to broadcast it. It will be a more "natural" playing of the age/gender role, less a performance? Or so I'd assume...
I don't know if that helps.