It isn't really a surprise in this case since both ethnic Mongolians and those with Downs syndrome are not in many Americans' social circles.
"Almost all" does sound like a bit of a surprise, but thinking back on it the only one I know for a fact I heard for the first time outside of a corrective context was my elder uncles friends who enjoyed self-depreciating jokes, usually with slurs for eastern Europeans in them. I first heard those as a child and only realized years later they were offensive. Most others, I think, I honestly have no idea when i was first exposed to them.
It's implied that someone is going around calling people with Down's syndrome "Mongos." "Mongol" is an actual non-offensive[0] word which means, unsurprisingly, someone who can trace their lineage back to the area around Mongolia.
I always thought it was a reference to valuable stuff picked from trash, which I understood to be slang from sanitation workers, but apparently that's local to the NYC area.
I don't know about other languages, but in German "Mongo" is pretty much a forbidden word as it is derogative descriptor for people with down syndrom and other visible defects, especially movement defects.
I don't know about other languages, but in German "Mongo" is pretty much a forbidden word as it is derogative descriptor for people with down syndrom and other visible defects, especially movement defects.
In the UK that would be "mong", for us Mongo is the planet Ming The Merciless is from.