In the dream to drink a cocktail, represents that you will deceive your friends as to your inclinations and enjoy the companionship of fast men and women while posing as a serious student and staid home lover. For a woman the dream about cocktail is a waning of fast living and an ignoring of moral and set rules.
Dream dictionary: Cocktail dream meanings
To dream that you are drinking some kind of the cocktail, means that you are trying to relax and have the good time. If the cocktail is enjoyable to drink, you will succeed in your life. If it is too strong, you should be careful while having too much fun. The dream could also indicate the fact that you try to forget the bad things in your life and concentrate on good ones.
You risk being cheated by your friends.