n. — Clothing, informal, at times jocular
a combination of blue jeans and denim jacket (see Image 1).
Type: 1. Origin — Known also by other names, such as Denim Dan style, Canadian tuxedo has gained currency in the youthful crowd as of the mid-2000s (see the 2012 quotation). The term is most popular in Canada (see Chart 1), but is not unknown in other countries.
See also: toque
- 2002  However, Canadian viewers will appreciate some of the border-savvy jokes. Farva is ridiculed for ordering a "litre of cola" at a fast-food restaurant. Later, when Farva sees O'Hagan in civilian wear - a denim jacket and blue jeans - he asks his boss, "Where'd you get the Canadian tuxedo?" Such moments may not be as exciting as the sight of Homer Simpson at the CN Tower, but they'll do. 
- 2009  "Don't try to wear a denim jacket with your jeans. You'll look like a jerk."
[...]
The show is peppered with "rudiments," quick hits of fashion advice such as the aforementioned warning against wearing denim jackets with jeans, also known as the "Canadian tuxedo." 
- 2010  This spring, go on and rock the Canadian tux, Tiyana Grulovic writes. Just don't wear matching tones.
There was a time when the Canadian tuxedo - the often dubious pairing of jeans with a denim jacket - was exclusively the domain of farmhands and Bruce Springsteen.
Recently, though, a funny thing happened on the way to the barn dance: The surfeit of chic denim working the runways has elevated the blue collar to haute status, making even the Canuck tux acceptable - within limits. 
- 2012  2. The Canadian tuxedo
For those of you who don't already know, the Canadian tuxedo is a classic jean-on-jean combo that has the mysterious ability to simultaneously repel and attract the opposite sex. Do it right, and you're giving off that sexy asshole lumberjack vibe. Do it wrong, and you end up looking like last season's hipster. Just remember: if it's good enough for Ryan Gosling, it's good enough for you.
- 2015  The Canadian tuxedo wasn't an overnight trend but has had a slow and steady burn over the past few decades.
"The Canadian tuxedo came out of the western-wear phenomenon that is dear to Albertans," says Jason Trotzuk, founder and creative director of Fidelity, a denim brand. "When you dress up in the West, you put on your best pair of jeans and a denim shirt. The pieces could both stand out on their own, but when you put them together you have a solid outfit." 
Images:
Image 1: Canadian tuxedo wearer on stone turtle (Source: Wikimedia Commons. Photo: rococohobo)
Chart 1: Internet Domain Search, 16 Jan. 2014