“Are you from Canada?”

When Aussies pick up on your “North American” accent, they will likely ask if you’re from Canada, not if you’re from the U.S. This is partly because they run into more Canadians than Americans, but mostly it’s because they know Canadians are sensitive to being mistaken for Americans, while Americans don’t care.

As for Americans: when asked that question, don’t be offended, it’s a great opportunity to strike up a conversation. Outside of tourist areas, Americans are a novelty.