I feel like gaslighthing foreigners about Haggis is a national pastime that people take part in with very little coordination or prompting. I guess its mostly gone now that people have instant access to Wikipedia, but I've had lots of these conversations over the years and people jump into it with such vigor and imagination that it's a little scary. The first time I remember it was about 2003, talking to an American guy at the bar in Usige Betha (now The Dram).