Generating geographically appropriate material

Performing at the only stand-up comedy club in Hong Kong has its advantages and disadvantages; english-language stand-up has never had the huge potential audience that it would in a big city like London or New York. On the other hand, the barrier to entry is lower, and there's less of the explicitly confrontational aspect one sometimes sees in London.

Further, as a consequence of it being drawn largely from an expat community, the audience appears to be more cosmopolitan than you might find in a provincial comedy club in England. If you went on stage in Bolton and asked members of the audience where they came from, I imagine the response might be the word "Bolton" repeated over and over again*. Whereas in Hong Kong, there have been nights with 20 nationalities represented. This presents an opportunity to get some improvisation done in advance, simply by having some appropriate material for every nationality that might present itself.

Now, there's at least 180 countries; does that mean 180 jokes? Probably not; let's pick the low hanging fruit/concentrate on the obvious hack material first. Or rather, I'll braindump what I know, based on common encounters, and then try to reorganise the list later by population size or inbound tourist numbers to Hong Kong.

Britain: Hong Kong used to be a British colony, so you are almost bound to encounter some Brits. English != Welsh != Scottish so you want at least one joke for each part of the United Kingdom. I've got one catch-all for "British" in general, nothing per nation.
Australians, New Zealanders - bound to be passing through on their way to/from the antipodes. I have one joke about my parentage and which rugby team to cheer on that does for both of them.
Americans: there's (metric) tonnes of them about. One joke about them; for bonus points you could have one about each state. Or you could lapse into cliche; everyone from New York is an Italian sociopath, everyone in California is a granola munching hippy, and all points in between are moronic farmer types. Seems to work for some people.
Canadians: 1 joke. See Americans ;-)
[No, really. I have one Canadian joke, based on that premise, but I insist it's a good one.]
Indians: something ill-advised about Pakistan/cows in streets/Ghandi is ill-advised. Unless you're Indian, in which case it's probably just hackery.
Singapore: they're clean, they've made chewing gum illegal, they have a merlion as their national animal. Should be some ripe pickings there, but I feel most of the carcass has been picked clean. Maybe something about how it's such an awful place, every year another F1 driver crashes there in a bid to escape the horror?
Japan: I've got a minute or so here that I'm happy with, well drilled and showing off some language skills.
Korea: not so common. I can say something about Kim Jong Il and welcome signs at Seoul airport - need a little more.
Hong Kong: ah, the locals. More homework needed here to be able to pinpoint districts, or work on commonality; public transport, wedding photos, badly worded signage. (Note that the last of these is horrible, horrible hack material. If you can buy 'amusing' collections of it at airport bookshops, it's not proper material. I wait to be corrected by some awe-inspiring Chinglish joke, but for the most part, it strikes me as "ho-ho-ho, look at the stupid foreigner" material. Maybe ok if you can read and write both Chinese and English fluently.) What have I got? Something on learning Cantonese. Probably anyone can get something on Cantonese (go beyond "it's difficult to say/write" and there's a wealth of options there) or on local cuisine. These are the jokers who serve up chicken feet, after all.
People's Republic of China (aka The Mainland): one joke (see British). Look what I did there! I just casually dismissed thousands of years of culture! (Or did I? Come along to a show and find out...)
Macau: Nowt yet.
Indonesia: Never had an Indonesian in the audience yet. Which means I can't assess the success of my joke involving an Indonesian girlfriend and some Australians.
Malaysia: Nope.
France: Rich pickings, right? Put in something about garlic and everyone will be happy.
Germany: See above, replacing 'garlic' with 'sausages'
Nordics: I have one catch-all joke based on general ignorance of geography. (Let the audience know they're smarter than you, and then point out that you made them think this because, well, they're not.)

I'll follow up on the PRC, Macau, France, Germany and the other gaps once I have something...

* Ok, the Bolton example is forced, and most likely quite incorrect: people may identify themselves as being from a neighbouring town, a suburb, an estate, but that is a bit harder: now you have different competing geographies in every club you visit, rather than a conveyor belt of national stereotypes happily delivering themselves every week to be lampooned.