Whether it is at work or at university, whether you are new at your job or tired of the daily routines, in Korea there are always reasons to go out as a group and have ‘a drink’. So people would ask you
술 한 잔 할래요?
(Sul han jan hal-lae-yo?)
which means, ‘Do you want to have a drink?’
술(Sul) is a term for all alcohol drinks and 한 잔(han jan) is ‘one(한) glass(잔)’. 잔 is glass in terms of ‘cup’ so it is all cups made of glass. You don’t use 잔 for windows or fake jewlery. The Korean word for glass in terms of material is ‘유리’. 할래요(hal-lae-yo) means ‘want to do’. (Remember, the 요(yo) at the end indicates the polite form.) So 술 한 잔 할래요? means, ‘Do you want to have(drink) a glass of drink?’
Instead of 할래요, you can use 마실래요(Ma-shil-lae-yo) which means ‘want to drink’ and is grammatically more correct. In spoken Korean, however, you can use both.
When you are finally at a bar people would ask you (this could even happen while having dinner)
술 잘 하세요? (Do you drink alcohol drinks well?)
(Sul jal ha-seh-yo?)
or to be gramatically correct,
술 잘 마시세요? (Do you drink alcohol well?)
(Sul jal ma-shi-seh-yo?)
Which is actually asking you if you can drink a lot. Remember, however!! Even when it comes to drinking, you cannot forget that modesty is always required, unless you are at a job interview. If you cannot drink a lot of alcohol but you still like to drink and enjoy, you can say
잘 못 마셔요.
Jal mot ma-shyeo-yo.
(I can’t drink well. / I can’t drink a lot. Koreans will take this as ‘Yes, I can drink a reasonable amount.’)
If you actually CAN drink to a reasonable extent which would be from a guys standard, about one to two bottles of soju or many cans of beer (for women one third to a half of that), you would say
(I drink a little.)
좀(Jom) is ‘little’ and is the short form for 조금(jo-geum). But even if you say ‘a little’, people would take it as being modest and understand it as ”can take SOME alcohol.”
If you can’t drink much or don’t want to drink, make some believable facial expressions or gestures and say,
못 마셔요.(Mot ma-shyeo-yo.)
which means, ‘I can’t drink.’ or
안 마셔요. (An ma-shyeo-yo.)
‘I don’t drink.
Please, don’t be too honest to say
네, 잘 마셔요.(Ne, jal ma-shyeo-yo)
Yes, I can drink a lot.
What people will actually think is that you can drink hell a lot, like a keg of soju, and if you have a heavy drinker around, he is definitely going to try to make you drink until you become sick. So don’t use the last expression unless you are confident to stay fine.