Ethiopia for me too.
And the first time I found myself in Ethiopia for work (circa 1997) I was eating Ethiopian food in the hotel restaurant (I love Ethiopian food) and they gave me waaay too much injera. Not possible to finish it. And all I could think of was my mom telling me there are people starving in Ethiopia. I actually begged the hotel to save the leftover food so that I could eat it the next meal.
They fed it to stray dogs 
Adding insult to injera…?
At other people’s houses, China. At my own, there was no guilt tripping about not eating everything. If you didn’t, a parent would finish it because we were on a tight budget and the servings were small. No cookie if you didn’t eat most of it, though.
Cambodia, early/mid 70s.
A generic ‘Africa’, but I only remember hearing it at school, not from parents.
Well-played sir 
Will you marry me?
Taking it that you’re male – unfortunately, I don’t think same-sex marriage is allowed in Ethiopia…
China, in the 1950s.
My parents used both China and India, presumably because at least some people were always starving in those places. I once asked something like “What about the kids in Biafra?” in a smart-alecky way. My mom didn’t skip a beat and said “Yes, it’s getting worse - clean your plate”.
Yes, people were starving in Africa when I was a kid.
But then again, my grandmother (who mostly raised me) had been born in 1899 the daughter of a poor sharecropper, my mother remembered not so fondly wartime food restrictions, and my father had been deported to a concentration camp, so you can guess that none of them would have looked too fondly on food wasting, even in the absence of starving Africans. My grandmother in particular would never throw away anything edible (or that had been edible). If it couldn’t be eaten by her, it could feed a stray cat or be brought to a nearby farm for the chickens or pigs. Throwing it away wasn’t an option.
Another one for Biafra.
It was China in the 50s around my home.
When I was a kid, we were stationed in India, so it really wouldn’t have worked. I could have marched out the door and said “Starving people of India! Please help yourself to my string beans!”
To be clear, I was answering in terms of the meme as it existed at the time of my childhood: I don’t think that my mom ever actually used it. It probably would have been redundant, anyway, since for a year or so of my childhood we had actual refugees living with us (and Mom still managed to pinch pennies so tight that we still all ate enough).