n. — slang, informal, Food & Drink
a 750-millilitre (previously 26-ounce) bottle of hard liquor (see Image 1).
Type: 1. Origin — Two-six derives from "twenty-six" or "twenty-sixer", terms that arose from a liquor bottle's 26-ounce capacity. Though 750 millilitres, the new standard measure, is just over 25 ounces, two-six survived the change from imperial to metric measures in the 1970s and early 1980s (see Canadian Encyclopedia reference). A "fifth", a reference to the former measurement of one-fifth of a gallon, is the current American equivalent (OED-3, s.v. "fifth" (B4)). Two-six is apparently exclusive to Canada (see Chart 1).
See also COD-2, s.v. "twenty-six", which is marked "Cdn".
See also: mickey 40-ouncer two-four
- Twenty-sixer is the older form that, since the 1980s, is being gradually replaced by the shortened two-six.
- 1957  The candidate could then retire for biceps and chest measurements and the counting of chest hairs, if any. For a windup, the candidate could do headstands, hang by the teeth, Charleston to the Tiger Rag while consuming a twenty-sixer of V.O. 
- 1967  Young spoke freely about his life as a drunk. He had his first drink when he was 13. "I stole my grandmother's Christmas bottle, a 26er. I was real smart, took it over to my boy friend's house and offered his dad a drink." 
- 1981  She was drinking up to 30 bottles of beer a day, Mr. Vankoughnet says; he was drinking 12 along with "a mickey or a twenty-sixer of scotch." They agreed to a trial separation for three weeks, he says. 
- 1990  After all, this is an author whose most recent hero, Kellen O'Reilly, the brainwashed cop of the 1989 novel Mindfield, reacts to anxiety by staying home, reading Camus and drinking "half a twenty-six of Stolichnaya." 
- 1992  The Canadian liquor bottle of that premetric day was called the "26er"; it held 26 imperial ounces or somewhat more than the American quart. 
- 1993  And when they come, they come as I have told them; bearing gifts and sacred offerings. John: a comb for my hair, mother-of-pearl. Dick: a pair of silk garters and a push-up bra, crimson red and lacy black. Roger a bottle of No. 5 and lacquer for my nails. And Ed, my main man: a two-six of lemon gin [...] 
- 2006  "They say that they'll pick you up in a car or stuff. There's different ways. I got phone calls saying that they wanted to haze me that they had a two-six of hard alcohol and they tell you to meet them somewhere," said the 16-year-old who stays at home and is afraid to walk the streets of Nelson by himself in case he is picked up. 
- 2010  "His ritual was he'd go to work and then he'd go and get plastered, and then he'd get home to his motel and he would fill up the bathtub with hot water and jump in with a two-six of vodka and drink himself to sleep in a warm bathtub. The idea was that in four hours, it would be cold enough to wake him up to get him up to go to work, and that's what he did," Dowse says. "There's so many stories like that." 
- 2011  McLeod recalls a frigid day last December when 23 1.75-litre bottles and 63 750-millilitre bottles, better known as a "two-six" for its former 26-ounce measure, were intercepted. "It was a staggering amount of liquor," says McLeod, noting one vehicle alone held about 50 bottles packed in plastic tubs. 
- 2014  Peer pressure is fueling the competitive edge of the videos. People are trying to one-up each other. In the past 24 hours I have watched a young woman drink two margaritas and half a two-six of rum. 
- 2015  The group’s self-titled demo was released back in July and hits as hard as a two-six of Alberta premium, but this is no stroke of luck. 
Images:
Image 1: A modern "metric" two-six of Canadian Club whiskey. Source: lcbo.ca
Chart 1: Internet Domain Search, 18 Jun. 2014