What if the voices in your head are literally voices in your head?

[IronWing]

Mouths, complete with tongues and vocal chords, whispering into your ears from the inside? You don't have sinus trouble, it's just that those mouths take up room. That would be bothersome, I think.

 

[BoomerD]

My dog tells me that the voices in my head are lying to me...

 

[GagHalfrunt]

Just scoop out a big portion of brains to make room. Most people don't use theirs anyway.