‘Mouth Breather’
Like yeah I don’t get this one. We all breathe through our mouths (and noses), because we have to. Yet I read this sometimes as it is used like an insult. So what are you saying? You’re insulting someone for doing what billions of other human beings have to do naturally?
I think it’s the “look” on your face when breathing out of your mouth. Like you are dumb, or dim-witted.
One of my great uncles would call us kids numb skulls. I heard it as one word as a kid and it wasn’t till I got older did I realize what he was saying.