Sorry to raise this topic over here, it was too heavy for me to answer all alone so I decided to share here to see some reasonable answer from those that have been in such situations. An hour ago, I went out with a friend of mine and it happens to be a drinking hall (beer parlor) where he got drunk and as well trading.
The question is, can you trade while you are already drunk?
Well... There are persons that can takes as many bottles of alcohol and no matter the quantity they take, it will have no effect on them. So if your friend is in that category then I see nothing wrong but if you mean that your friend was actually drunk then it's something to worry about and he might make costly mistake while trading because he's not in control of his senses.