I have only one question: Is she patiently standing by, in suspended animation, while you check in to the “teeming millions”? It’s what, almost 13 hours since she asked “OK?” Was her last thought “I’m gonna wait here expectantly until you come up with an answer, OK?”
Clutch hand to chest, make choking sounds and fall over.
Another option is to go wildly on the offensive. “Well, FUCK THAT NOISE. If that’s the way you feel we have nothing to talk about!!!” And glare angrily, maybe throw the newspaper you were reading to the ground.
Light yourself on fire?
“Dear, I’m an idiot. Could you repeat that please?”
If she insists on knowing what distracted you: “I was wondering about this stabbing pain in my left eye, but it’s gone now. What did you say again?”
Not voting, or reading the other replies yet. Say something honest, or close to it, like “Oh crud. Sorry, honey, I missed the last thing you said because I was thinking about what to get you for your birthday/how pretty your hair looks today/that song you played for me last night is stuck in my head. I’m such a dolt. Could you tell me that last bit again?”
I would be an awesome husband. 
P.S. In my house, we call zoning out “getting stuck.” So if this situation happens, we just say “oops, got stuck there for a sec.” Well, I do.
Dear, I heard every word you said, but it still doesn’t make any sense - could you try that one more time, maybe slower?
her - I SAID TAKE OUT THE TRASH!
Me - Oh, good - I thought you said something about looking at a rash - imagine how embarrassing it would have been if I had said “sure, bend over”.
“Ask again later!”
Yes dear. As long as it doesn’t cost a lot or involve me doing any squaw work:p
Everyone I know realizes that I have a hard time hearing sometimes, even though I’m trying. They can’t get mad at me for a physical problem.
I’m sorry, what was the OP about?
“Oh, crap, the laundry!” and go do some laundry. There’s always laundry.
Pop a smoke grenade
Make escape in a serpentine motion…don’t look back!
If you do make a mistake and piss the wife off, remember to sleep on your stomach for a while. Had every man followed that advice we would have never heard of John Wayne Bobbitt.
I need to use this.
Ear wax eloquently
Having tried this one, I’d recommend against as the response is not at all mixed. Rather than use that one again, I’d go with, “I’m sorry, I wasn’t paying close enough attention and I think you just said something important.”
Yep, because missing what your wife was saying is the same as abusing her for years.
A while back my live-in girlfriend of a decade (so, wife) noted that I would often say, “mmm” when in this situation, which she took for assent, and then would get annoyed later when I had not done whatever the hell it was I was supposed to be doing. So, she told me that if she starts talking while I am concentrating on something else and therefore not listening, to just say, “Sorry, I’m not paying attention and won’t be doing what your are asking.”
She asked what I thought about this idea.
I said, “Sorry, I’m not paying attention and won’t be doing what your are asking.”
I don’t know why she turned that color of red, it was her idea.
I usually go with “Sorry. I wasn’t paying attention to any of that. Say it again.” It works just fine.