Stuff like this happens because of silly nationalist pride, and ignorance. I wouldn't be too bothered by it. America has as many things to make fun of as France, and so does Canada. No country is anywhere near perfect, and if you're from one country you'll probably find some way to criticise another; just as the people whose country you make fun of will be able to make fun of your own. That's just the nature of overzealous nationalism, ignorance and bias. That, and people who are just being silly and likely mean no harm.