n. — informal, slang, especially Ontario & Western Canada, Maritimes
a case of beer containing twenty-four bottles (see Image 1).
Type: 1. Origin — The term appears to have originated in Canada. In other locations, such as the US, a pack of beer with 24 units, either bottles or cans, is more commonly referred to as a "case" or a "24-pack". Use of the informal two-four is nearly exclusive to Canada (see Chart 1). Note that not every Canadian brewery packs their beers in cases of 24. Cariboo Brewing, from Prince George, BC, for instance, uses 20-packs, while Alexander Keith's, from Nova Scotia, uses 28-packs. Central Canadian breweries, however, generally offer 24-packs.
Chart 2 is a manually corrected regional search, casting aside any false hits. It shows that the term has a distinct regional pattern: popular in Ontario and all the way to the west coast, not found in Quebec and New Brunswick in our data, while most popular in Nova Scotia. Written attestations are not found in Newfoundland & Labrador and the Territories.
See also ITP Nelson, s.v. "two-four", which is marked "Canadian Informal" and COD-2, s.v. "two-four", which is marked "Cdn informal".
See also: May Two Four two-six May long
- The term now has the status of an informal identity marker of an informal type. It is known by outsiders, as can be seen in US president Barack Obama's casual and humorous comment during a state dinner for PM Justin Trudeau:
“And tonight, we want our Canadian friends to feel at home. So this is not a dinner, it's supper. We thought of serving up some poutine. I was going to bring a two-four. And then we'd finish off the night with a double-double. But I had to draw the line at getting milk out of a bag -- this, we Americans do not understand. We do, however, have a little Canadian whiskey. That, we do understand.” from "Remarks by Trudeau, Obama at state dinner" Newswire of The Canadian Press, Toronto, ON, 10 Mar 2016.
- 1978  Beer drinkers who feel that a 12-pack isn't enough to quench their thirst and that a two-four is too much no longer have to buy a six-pack to fill the gap 
- 1985  I looked over my shoulder into the back seat. Damn. The two-four was smashed and was leaking all over my back issues of Penthouse. Damn. It was bad enough being out past curfew - on the worst night of the year - let alone driving with an open case of beer and causing a crack-up. 
- 1992  The two-per-cent drop last year may not sound like much, but expressed in hoser terms, it's a lot of beer: about 33 million cases of ''two-four'' (that's a 24-bottle case).
- 2002  She then gives the bride a card for a free two-four of Bud Light, telling her, "... you can always say I love you with a case of Bud Light." 
- 2012  "As a place for people to experience beer, I don't think it's the best shopping environment," said Meek, in reference to the many Beer Store locations that consist of little more than a wall with dozens of different small bottles showing the different products.
"Not too many people go in there and say 'hmm, I wonder what I'd like today.' You go in and you get your 2-4 of something." 
- 2013  Manitobans paying more for a two-four It's costing more for Manitobans to take home a case of beer this weekend. 
- 2016  Then the May 24 weekend comes, (and no, my razor-sharp oldest daughter, this is not a weekend named after a two-four of beer, nor is it absolutely necessary that one be consumed in celebration), and we load up everything we have collected over the long winter and head off to the lake.