>>10404861Culture is often a hard thing to define if you're immersed in it, so grugs tend to distinguish themselves against the culture other than their own, which they're most familiar with. American and Canadian culture are fairly similar though, and because of their massive world presence and media machine American culture is very influential in other countries.
Plus, a lot of aspects of American culture that aren't similar to other western countries is largely idiotic, obnoxious, or both, all of which adds up to make the "we ain't yanks" is a really expression of culture to grab at, if a largely shallow and unnuanced one.