"those people with a speech impediment"

The people, formerly called Hottentots, did not suffer from speech impediments, unless, of course, not being able to speak Afrikaans or English is taken to be a disorder. (Non-natives speakers as stutters and stammers is a trope in ancient times, e.g., the Greeks called all barbarians so because they stammered (or said bar bar bar).) Jokes and stories told by groups about their neighbors falls under the heading of blason populaire in folklore. (See link and link.)

Ceci n'est pas un seing.