When ordering drinks from a bar or food from a restaurant, most of the time you'll be dealing with a non-player character (NPC) that is smart enough to serve you without a game master (GM) controlling the NPC. The NPC knows what can be prepared for your consumption and is just waiting for you to ask them for it.
The NPC is smart enough that if you ask them for something, but what you ask for matches more than one of the things that can be prepared, that they will ask you to pick from a smaller list of things.
The trick when ordering is to try and do it naturally. You also want to avoid using words that are the same in more than one option. If for example, the NPC offers the options 'beef tacos or chicken tacos', avoid using the word 'tacos' when replying to the NPC. Just say 'beef', or 'I'll try the beef, but it better be real meat!'.
The NPC will attempt to figure out how many of an item you want. For example, just tell the bartender you 'want three shots' and you'll be on your way to drinking oblivion.
There might be other things you can talk with such characters about too, but thats definitely IC.