When you live in America, there are two national stereotypes that pop up frequently and are as pervasive as they are puzzling: Brits have bad teeth, and Canadians are too nice.
The stereotypes are not only pervasive, they are thought of perfectly harmless and worthy of making fun. If you have watched American comedies, you will have seen the buck-toothed, yellow-stained Brit smile. Also common, the Canadian brute that turns all polite.
In fact, sometimes the Canadian stereotype is geared towards the brute that is too polite. The best example I can come up with is Robin Scherbatsky, the beautiful tomboy that is the central character of How I Met Your Mother. She is depicted as someone that was trained to be a man by her domineering father, who lives up to the expectation, but who also is unfailingly hyperpolite.
Oddly, in both cases, the stereotype says more about the people holding it than about the people stereotyped. You see, Brits and Canadians are close enough to Americans to be able to routinely pass as such. They are of the same genetic makeup, they dress largely similarly (although I am pretty sure my British friends would object to that), and they have largely compatible social interaction structure.