Asking someone to repeat themselves casually
1) For English speakers of all flavors: if someone speaks to you and you don't understand them (for example, maybe they spoke too quickly or mumbled), how do you ask them to repeat themselves in a casual setting (e.g. with a family member or close friend)? [I'm a native US English speaker from the south and recently realized I almost always say, "Do what?", regardless of whether or not they mentioned anything to do with 'doing' something]
2) Would you ever use the following construction, or some variation thereon?
"We were neither of us going to argue with her at that point."
"They neither of them wanted to wake up that early."
[I've used them in my writing on several occasions and never gave it much thought until another friend said it sounded strange; I'm not quite sure where I picked it up, but I've seen it used in published novels too, and now I'm wondering if it's all that common or maybe restricted to certain dialects?]