Just start using the word "retarded" more often. Watch as all the "triggereds" come out of the woodwork. The irony being that actual retarded people are unlikely to be triggered by the word "retarded" at least unless until people told them they should be triggered by it.
Plus if you sugar-coat things or use substitute words you're still saying the same thing so you replace a "bad word" or "offensive word" with some other language and the replacement itself becomes a "bad word" or "offensive word" at some point, repeat. Isn't it better to just straight-up tell people like it is?