Nitwits don't do anything. So have them say silly nonsensical quotes. It doesn't add anything to Minecraft, but neither do Nitwits. (But people love them!)
You go up to a Nitwit, attempt to interact, and instead of bringing up a Trading modal it instead brings up a popup that just has a silly gibberish quote in it.
"Cats, dogs, and babies, it's Tuesday!"
(found this on the internet)
It's silly. It's nonsense. It's gibberish. It makes you want to pause, shake your head, and say "You Nitwit."