But did you refuse the drink specifically because you where underage or because you didn't want to drink? If that same party had been in country where you where legally allowed to drink would you have drunk then?
(I'm eliding and slightly distorting a lot of surrounding details both because my memory of the time is often fuzzy and because I don't feel inclined to detail too much of my ancient personal life here. The central points, however, I'm clear on.)
It might be worth adding, to circle back toward the original topic, that while I notice that this isn't “normal” in much of the US (where I live), people around me have wondered whether I got this tendency from somewhere else. (In fact, I had one (non-Japanese) Asian immigrant parent, and while that one was quite chaotic about following the local laws, it's possible that more indirect connections had strong subtle influences.) Some societies are much more regimented and/or conformist, and Japan is frequently described as both (not that I would know what bearing it has on these specific questions). The “natural pattern of rule breaks” is not universal, neither in cultures where it's nearly-expected, nor between cultures.