Translation:What drinks do you have?
"Y'all" is spreading in American English, though. "Overall, the use of y'all has been increasing in the United States, both within and outside the southern United States. In 1996, 49% of non-Southerners reported using y'all or you-all in conversation, while 84% of Southerners reported usage, both percentages showing a 5% increase over the previous study, conducted in 1994." (from https://en.wikipedia.org/wiki/Y%27all#Regional_usage) This is also anecdotally confirmed by various Internet articles, as well as my personal experience.
The problem is that there are multiple people being addressed so it is assumed that the unknown drinks will also be multiple, even if it turns out that they are all the same. You would not use the singular "drink" unless you knew in advance that everyone had the same drink and then you would not need to ask the question (and even then it would be a pretty weird/unusual question).