A Dallas-based pizza chain called "Pizza Patron" decided, on a promotional basis so far, to accept Mexican pesos in their stores, which are scattered throughout the southwest, as far north as Denver.
The result (predictable but sad): People with nothing better to do are sending threatening emails.
I used to work for a large Seattle-based coffee chain, at a store in the Seattle area, and we accepted Canadian currency. Now, I probably only saw it 2-3 times in the three years I worked there. I also got zero calls saying that I was on the side of the Canucks and this is not the "United States of Canada." (As much as I may sometimes wish it were).
Dude, it's money. And it's good business. If it isn't, they'll stop doing it. (Conservatives, isn't "good business" supposed to be a good thing? I guess only when conducted in English).