ijuin wrote:America is a country where the normal serving size for beer is neither one glass nor one bottle, but rather the pack of bottles in which they are sold. Drinking six to twelve bottles or tins at once is quite common among enthusiasts.
No real American would drink twelve tins at once, or even a single tin of beer, because we don't sell beer in tins. We sell it in cans. It is only acceptable to confuse tin and aluminum in the case of foil, not beverage cans.
That said, it's true that many beers in the U.S. are drunk in large quantities, but that's bound to be true in the U.K. as well, since their beer is just as weak. In a place like Belgium that has much stronger beers, it wouldn't be realistic to just down a twelve-pack like it's nothing. Because some people enjoy the experience of drinking lots of beer, light beers get a lot of sales and the most popular beers are pilsners with light color and taste. Now that craft beers have exploded onto the scene, with strong and diverse flavors, some people still want beers that they can drink in quantity. So they sell "session" beers with lower alcohol content (but not necessarily lower price) for that purpose. These are similar in strength to British beers traditionally drunk in sessions (3-4%, or sometimes a bit higher) but with whatever flavor (often a pale ale). In all cases, the standard size for a beer is 12 fl oz, but larger sizes are also somewhat common, up to a max of about 24 oz for a traditional beer and 40 oz for a malt liquor.
In a bar, people don't buy packs of beer (obviously), but the old staples like Budweiser are still very popular. (Many people, particularly younger people, can't stand that flavor, but plenty still like it.) Most draft beer servings are 16-24 oz, though 16 is sort of a standard. Beers larger than about 21 oz are sometimes called "tall" or "tall boys." Expensive or very strong beers are sold on draft in lower quantities, as low as 8 oz for very strong porters and the like. Beer in the bottle might also be sold in "buckets" during special events like football games, where a "bucket" typically is a literal bucket with 4 or 5 bottles of beer in it, sometimes on ice. The idea is to get 4 or 5 beers at a slight discount compared to their usual (already low) price.
At a party, beer may be pumped from a keg. Parties featuring beer kegs are called "keggers" and are particularly popular in college fraternities. You can look up the standard keg sizes on Wikipedia (can't remember exactly), but usually people get a half keg or pony keg rather than a full keg, since that can be hard to finish in a single party and frustrating to transport. Bars that are large enough will use full size kegs for their draft beers, and bars with less space will get smaller kegs.