There are lots of wonderful people from the US of A. This trick is not for them. This trick is for the arrogant asses who we occasionally run into. The purpose is to give them a zen slap that may wake them up from their ignorance and arrogance.
Pretend that you have never heard of the USA.
It completely breaks their brain, and forces them to try and fire neurons that are well out of practice. Force them into new and exciting fields such as geography and history, and if they come along for the ride, give little indicators that you may be understanding what they are saying, but turn it back int a question. Key phrases to help this little ruse.
"America? There are 21 countries. Which One?"
"United States? Nup never heard of it"
"Your English seems passable. What is your mother tounge?"
"Are you guys part of the Commonwealth?"
"I can't be expected to know all the ex British colonies, you know."
"Is that one of the colonies that couldn't hack it?"