What is a mouse breather?

And I have seen the idea used in a couple of murder mysteries, where a victim was tied up and their mouth taped closed, leading to unintended death by suffocation. It lives in the same story space as the rare thin- skulled individual, where a tap that would make an ordinary person unconscious becomes a death sentence.

“He's such a mouth breather. Why do you hang with him?”

Oh dear. I'm picturing tiny little breath masks for rodents. Maybe they're working in a hospital, or seated on a plane where the masks drop out of the ceiling. Doing CPR on a fellow murid who got away from the cat just in time.

Are you struggling with weight loss and finding it hard to stay consistent? What’s your biggest challenge when trying to lose weight at home?

And the adorable little mouse breathers now have a space in my imaginative visual vortex. They're just so cute.

Cute as the notion is, I think the phrase you're looking for is mouth breather. As in someone who breathes with their mouth open. There are a number of medical conditions that can cause chronic mouth breathing, when the nasal passages are blocked. But calling someone a mouth breather outside of a medical context usually means you think they're slow or stupid.

I suppose there might be some obscure sect that inhales rodents, in the way that there are snake handlers. Or an odd addiction to sniffing the critters. But I've seen neither hide nor hair of such practices.

What is the meaning behind people claiming to hear voices of God in their heads without anyone else hearing them? Is this a sign of mental illness or possession by an evil spirit?