How can you tell if their Canadian?

So the other day, my brother was taking my nieces school shopping. Well my oldest niece was looking really hard at the back of one of her earring tags that they had just purchased. So she asked my brother, Tyler, "how can you tell if people are from Canada?" Tyler said, "well I am not quite sure because they look like you and I, why do you ask?" Well then the funny part comes, Taryn said "well then how do they charge them a different price?" So because you all know how on the back of books and so forth, it says the Canada price and the USA price. I thought it was really funny.....I am sure she will love that I posted this.