It's all about context. When someone says, "Let's go grab a drink", they clearly don't mean root beer. All that other shit you said sounds pretty faddish.
I'm gonna side with TC. "Let's go grab a drink" works, but "you wanna meet us for cocktails?" works just as well.
There is clearly no gray area when you say cocktail.....alcohol is obviously involved, when I run a race and I want a "drink" I need water....
Agreed, but in fairness, in the example I gave, I think it is pretty obvious that we are talking about alcohol both times.