As all the Canadian posters who have chimed in on this thread have said, it's a well-known stereotype (amongst Canadians, anyway). It's not a stereotype based in ethnicity or used to discriminate against an identifiable group, it's more along the lines of saying that Canadians love hockey.
Or "Germans love David Hasslehoff." Exactly. I'm actually very surprised that there's more than one person in this thread who's not familiar with the generally-joking stereotype. I shouldn't be surprised, obviously, different strokes and all that, but it's definitely not confined only to Canadians. I'd have guessed it was at least as commonly known as the undeniable fact that all Canadians say stuff like "oot and aboot" all the time.
I really don't get the "complimenting one group insults another" idea, either. Taking that to it's logical (to me, at least) conclusion would mean that if I say "Man, that Betty is one smart lady," literally everyone who hears me say it or somehow becomes aware I said it could take me to task for calling them dumb. No.