People who mutter under their breath, whisper while they read, or natter quietly to themselves when they aren't speaking to another soul, need to have their lips stapled together. All that comes to mind when forced into close confines with such persons, is shut the fuck up.

I had a friend at one time, who couldn't breath without making noise - and it's noise he could have easily avoided making, too. It drove me batshit, like that hair that you can't quite get that's gone down the back of your shirt.