Oh, god, tourist stories! I have so many, it's amazing. See, I live in a tourist city where roughly half of the visitors are from the states. LAw of averages says that most (not all) of the stupid questions will therefore come from a U.S. citizen.
Some of the funnier ones:
* "What's the name of that tree?" "Um, that's a douglas fir." "What's the name of that tree?" "Also a douglas fir." "What about that one?" "Uh, a Douglas Fir." "Oh. Is that one a Douglas Fir, too?" "No, that tree's name is Steve." "Really?" "No."
* At the airport once, in August, and watched a plane arrive from L.A. Watching the people getting off. And one younger woman, putting on a heavy winter jacket while getting off the plane. Before she even got inside the building, she realized she was incredibly hot, and took the jacket off. Upon coming in, I heard her telling her friend "It's a lot hotter in Canada than I thought it'd be. We should have brought our swimsuits." And then asking the desk if there were a place in "Canada" where she could buy a swimsuit... and, before getting an answer, explaining what a swimsuit was.
* My personal favourite, because it happens ALL THE TIME: Americans that believe Canadian money isn't real. And so throw it away. I've seen tourists spend an American twenty on a two dollar item, and get a bunch of toonies and loonies back. They'll keep the quarters, dimes, and pennies, but will literally give away the two-dollar and one-dollar coins, often as tips. MAny tourist shops realize this, and will only give you back two-dollar and one-dollar coins (they ain't stupid!).
That being said, there are plenty of stupid tourists from all over the world that visit my neck of the woods. From the asians who flew to Vancouver island because they wanted to go to Vancouver (look at a map before booking a flight, okay?), to the brits who decided to inform me (and they weren't even drunk!) that we were wrong to call the sport "Football". That "football" should not be called "Soccer". (and the funny thing was, I hadn't even been talking to them, I wasn't talking about Soccer, and there wasn't a soccer game on any nearby TV screen!).