Well, if you’re on death row and it’s your last meal you order a McRib and a Shamrock shake.
mmm
Do you usually get what you want when you order?
- if Yes, you are ordering correctly
- if No, you may want to try some of these suggestions
That’s really all there is to it. Well you have those people who take a very long time to order, but that’s not in the spirit of the OP.
You forgot to say “Please”.
These are human beings you’re speaking with. There’s no cause to be impolite.
Good evening. Could I possibly avail myself of my choice of your fine comestibles? If so, I would appreciate, at your convenience, a hamburger containing cheese and a portion of fried sliced potatoes. Thank you.
Both these constructs are far too risky. “Can I have” contains some level of doubt, and you never know, they may deny you your order just out of spite. ‘I will have’ is far too confident, and you run the risk of looking foolish if they turn around and say they’re out of stock.
I recommend being direct. “Cheeseburger and fries”. Saves face, saves time. Everyone’s a winner.
I don’t think you understand the idea of implicature in language:
When some people say, “Can I have a cheeseburger and fries?”, they mean, “I’m ordering a cheeseburger and fries.” They are using implicature. It is very standard to imply what you mean rather than state it absolutely literally. In fact, some people would find it to be slightly curt and impolite to say, “I will have a cheeseburger and fries.” You need to learn more about how language works. Implying meaning rather than stating everything absolutely literally is a standard part of all languages.
“I will gladly pay you on Tuesday for a hamburger today.”
“Can I get a cheeseburger and fries please?” Polite, but wrong.
“May I have a cheeseburger and fries please?” This is proper grammar.
By the way, it’s so clean.
Yes. Moreover, the OP–like everyone–does the same thing in all kinds of other contexts, too, and probably doesn’t realize it. We all do.
All I know is if you are in a drive thru, dont order everything on the menu! Unless you use those words only! 
Depends where you’re on Death Row. If you’re in Texas, this asshole ruined it for everyone.
Funny, since I eat burgers all the time and am in great shape. A staple of a diet that helped me lose 40lbs of fat and get back to my late teens/early 20s shape while in my 40s. All the fat asses are sitting around skipping the burgers but eating chips and candy.
True, but a lot of times in life implying doesn’t get you what you want. I learned that I had a habit of being way too subtle about some things and had to start saying exactly what I want. It worked.
Occasionally when dining where I am known, I like to ask the server to ask the chef to prepare whatever he thinks I’ll enjoy. There are two places where I can do this and always end up very happy.
Mine is “I’ll just have a cheeseburger, please. And whatever extra cats Two Many Cats has, but on the side. Thanks”
I say “can I have…?” or “I would like…?” and end with “please”, always…without exception.
It’s certainly uncontaminated by chee…
SHUT THAT BLOODY BOUZOUKI UP!!
“On the side”.
Had an acquaintance ( friend of a friend ) who was a 24 carat pain in the ass when eating in a restaurant/diner. Everything “on the side”. Hogged all the table space with all his on-the-side stuff.
While I never saw him order beef stew, I wouldn’t be surprised that if he did, it would be like:
“Beef stew, with the beef on the side…with the potatoes on the side and the carrots* on the side*…and oh…can I get extra gravy on the side”.
I’ve noticed people ordering food by saying “I think I’ll do the…whatever”.
Dave Barry once suggested that restaurants add an extra charge for every item ordered “on the side” that is immediately dumped into whatever it was on the side of, thus negating any benefit of ordering it “on the side” in the first place. 