Also there’s no apostrophe, they abandoned grammar for…idk what. Clarity of signage or something. Tim Hortons not Tim Horton’s!
You go there for (a) coffee and doughnuts, (b) bagels and cream cheese © soup and sandwiches.
If you want a standard order, an everything bagel with herb and garlic cream cheese and a large double-double would make nobody blink. A hockey player would probably get at least two bagels though. If you are buying for a bunch of people you can get a box of timbits (10/20/50, though the 50 is a new size and used to be 40 until last year.)
Double double means two creams, two sugars. If you aren’t getting that, you tend to say explicitly what you want (e.g. most people don’t say say single single). I order a coffee with one cream, for example. But they always add it for you, you never add your own milk/cream/sugar.
(The cream is also 18% cream which I think most people don’t know. Richer than table cream at 10% even, which is another reason it tastes so good.)
Finally, if you are on a road trip in Canada and you need to pee, you look for the Timmies in the next town/roadside stop. It is extremely useful because you don’t need to buy anything, but you always want to anyway.