Or any fast food place, for that matter.
If you walk in, order 100 hamburgers and pay in full, will they make them for you? Is there an upper limit to how many they’ll make? If they do make them, how long do they make you wait while they make them? Do they have an accurate inventory of how much they have?
My wife and I were discussing this tonight because we only discuss important topics. 
If they do make them, I suppose you have to wait as long as it takes to make them. The serious question is: How long does the next (several) person(s) in line have to wait?
Answer: As long as it takes to make 100 burgers for the guy ahead of you!
You can order, and they may make them.
McDonald’s is a franchise, so they could refuse from location to location.
Nah, when I worked fast food we’d stagger large orders to keep the customer flow smooth.
I once ordered 50 hamburgers at McDonalds to take to a local group home. They made them. It didn’t take all that long. They may serve hundreds of burgers along with everything else at a busy restaurant at lunch time, so 100 burgers isn’t outrageous. I’m sure they won’t make all the rest of the customers wait for your order.
Answers will vary…with a franchise there is typically an agreement between the franchisee and the franchisor to operate in a certain manner and following guidelines spelled out in various rule books and etc that the franchisor promulgates.
However, generally the franchisor sends out representatives for on-site inspections around once a month (most major American fast food chains) to ensure compliance and some level of standards across a large, franchised food chain. What this means is basically every day except for those on-site inspection days the behavior of the restaurant can vary dramatically (or they can follow the rules the whole time.)
I’ve known of some local franchisees who for very large orders wanted “on demand”, if it’s during a busy time they decline the order because they say they are unable to both fill the order and service the rest of the customers. The logic is that while the one big order would be a nice bit of money, it’s probably worse to extremely anger 30-40 customers by making them wait than it is to lose out on the one big order. Others will try to service the large order, usually by devoting a member or two of the staff exclusively to that order while the rest of the crew keeps everything else running. But depending on what chain we’re talking about it just may not be feasible and you’ll have significant slow down in service. (A Subway franchise for example can sometimes have only a single person working.)
I think McDonald’s could handle 100 hamburgers pretty effectively, it’s a very high throughput operation at most McDonald’s stores. A place like Subway probably could not physically serve 100 sandwiches without it being an advance-notice catering order. I have a tenant that is a Subway restaurant and I know the owner pretty well, depending on the day of the week they will sometimes have under 250 bread made for the whole day so depending on when the order comes in they may physically not have enough bread. Then they’re basically looking at taking a very, very long time to satisfy the order as they have to bake multiple batches of bread while assembling the sandwiches, and the baking process takes like an hour assuming the frozen bread is thawed and ready to proof.
But they do offer catering and bake bread in advance if they know this kind of thing is going on.
A friend of mine manages a taco bell, and they just catered a wedding last month. It took a couple of hours to do 500 tacos (but of course the couple put in the order a couple of days ahead of time).
I fairly regularly send out for 40-50 double doubles and a like number of fries when I feed the shop.
Never a problem.
Since you mentioned In N Out, here’s a guy ordering a 100x100 (a single burger with 100 patties and 100 slices of cheese.)
Call first. Give them a chance to fill the order at their own pace. Unless you like to wait at fast food joints?
Don Imus’s famous prank phone call from the early 70s: 1200 Hamburgers to Go
Yup.
A pretty classic move for our sales people (chemical industry) when they visit a shop where we’re trialing a new product is to stop by a McDonald’s on the way there and order 50 or so Egg McMuffins, Sausage biscuits, etc (trials usually start early in the morning.) Usually takes the McDonald’s maybe 15-20 minutes to fill, which actually is not bad. Then when they get to the shop, before meeting with the owner/plant manager, they find the production manager and set up a spread in the employee break room.
It’s amazing - workers trying a new product? They hate it. It’s 100x worse than the old product, it smells funny, makes them sick, doesn’t work (never mind that it’s basically chemically identical)
But give them some free food first - Hey, we like this new product, works much better, doesn’t smell as bad as the old stuff, and we like this new salesperson better!
Reminds me of a little ditty I heard decades ago:
Going to McDonalds,
Gonna stand in line,
Order a billion hamburgers,
Watch 'em change the sign…
We took band/orchestra trips in high school. The bus would stop at places where there was several fast food places within walking distances. That way we all didn’t pile into McDonalds. Back then we just picked a place and walked over for a burger and returned to the bus. Even then it was crowded.
“Taco Bell” and “wedding” —Wow.
I didn’t know that it’s possible to combine those words in the same sentence. 
(sorry, mods..yeah, I know I’m off topic..But it’s after the first 10 posts. And I’m typing in a state of shock from trying to imagine that wedding. )
Sounds like a classy affair. Which truckstop was the service at?
My dorm wing ordered ~600 hamburgers one night (it was 50c hamburger day or something).
Brian
It would go along with those Twinky/Snoball 'cakes’ 
Maybe it was for a Mexican family who wanted the food not as a main dinner course, but to keep their large number of extended guests happy for lunch during the wedding day or a pre-wedding get-together. Reasonable no?
Obligatory Woody Allen clip.
