Sometimes the questions are so silly/dumb that no reply is needed.
A woman was watching me read a German newspaper and asked, “Do you read German newspapers in German?”
Most people in the room looked at her like she was insane, so no comment was necessary.
I don’t know how true it is, but this one has been passed around as a coroner’s real answer to a dumb question in court.
Q: Before you signed the death certificate, did you take the pulse, listen to the heart or check for breathing?
A: No.
Q: So, when you signed the death certificate, you weren’t sure the man was dead, were you?
A: Well, the man’s brain was in a jar on my desk, but I suppose he could have still been practicing law for a living.
My favorite (high school) are the ones that ask "Did we do anything yesterday? I usually reply “no, we just sat around and talked about our feelings.” It’s amazing how many will nod and walk away.
As far as the baby thing goes, I still think it’s a silly question. “How’s the baby?” or something serves the same purpose and doesn’t put anyone on the spot.
Hipster Doofus: I don’t drink and never will. Why do people insist on socializing by putting toxins in their body?
Me: It helps us put up with people like you.
I always ask/answer this question by switching it to “easy”/“difficult” baby. As in,
“Is he a good baby?”
“Oh, he’s a little easier than his sister was, but maybe that’s just because we’re more experienced as parents now.”
Were there other people who was invoking this, or did you just not learn to find a way to avoid it? If I had a friend like that, I’d just say “That’s interesting” or similar after a couple of times.
When my husband asks me to remind him to do something, I’ll often turn right around and tell him “Don’t forget to do A” immediately. Then he rolls his eyes, and tells me when he wants me to remind him. One of these days, he might remember to tell me when he wants reminding before giving me a chance to be a smartass! 
What’s wrong with the perfectly good verb “to be at”?
Q: Why are you so musical?
A: Why do you breathe?
“No, we left him out of the fridge too long and he’s gone bad.”
Nothing, until it’s used with an adverb whose definition is “at what place.” That kind of repetitive redundency is negatively frowned upon.
I thought for sure this was going to be about someone asking President Obama if he has his own computer! But Obama had some fun with it.
I believe the problem is that it ought to be “Where you at, dog?”
It’s not a question at all. No one who asks “Is it a good baby?” is actually concerned that it might, in fact, not be a good baby. It’s a conversational invitation for a new parent to gush about their child.
Yeah, I have to agree, it’s incredibly annoying when you say “really?” and then the person responds with something like “no, I’m fooling you,” as if I was saying “OMG YOU ARE YOU LYING TO ME YOU MUST BE LYING TO ME THIS IS SO UNBELIEVABLE”
That’s about on par with people who say “the ceiling” when you ask “what’s up?”
“Nothin’ but the rent!”
This one’s fresh:
My wife calls me and says, “The line was busy just now. Did someone call?”
“Yes, it was your aunt calling to wish you a happy birthday.”
“Did you tell her I was out?”
“No, I said you just didn’t feel like talking to her.”
Real life incident:
Guy calls up, I answer the phone.
Guy: “Is <brother name> there?”
Brother: <whispering> “Tell him I’m not here!”
**
Me:** <reflexively> “He says he’s not here.”
Brother: <facepalm>
Well, since the thread seems to have turned into “Snarky responses to perfectly normal questions”, I would like to say that I really, really, really hate people who say “All day” when I ask “Is today Thursday?”
Similar thing happened to a friend of mine when he was a teenager. First week on a new McJob, and my friend decides to call in sick and go to the beach instead. Right in the middle of telling his boss he’s so sick he can’t hardly get out of bed, his sister picks up the extension and says, “Chad, dad says if you’re not going to go to work, you have to mow the lawn.”
If they’re twins it’s OK to ask which one the evil one is.