I Have Nothing to Say to That

One character is arguing with another who (s)he thinks is being stupid, when the other makes a point which renders the first momentarily speechless. Related to Dumbass Has a Point. In comics, as per the Webcomics example, signified by '?'. In live action, usually signified by character 1 pausing open-mouthed, possibly with a finger in the air.

Related to Shutting Up Now and Sarcasm Failure.

Examples of I Have Nothing to Say to That include:

Film

In Tootsie:

Sandy: A guy named Les is sending you flowers?
Michael Dorsey: Yes. He's a friend of mine. He can't eat candy; he's diabetic.
Sandy: Why is he thanking you for a lovely night in front of the fire?
Michael Dorsey: [long pause] My mind's a blank.

Live Action TV

In one episode of Stargate SG-1, the team hesitates at the prospect of getting to the gate, which is guarded by a legion of Jaffa. O'Neill is arguing with a scientist about how to go about it, when the scientist just goes, "But you're SG-1!" O'Neill has no response to that except to shrug, and go ahead and kick some ass.
In an epsisode of The West Wing, Sam Seaborn gets his ass verbally handed to him by Blonde Republican Sex Kitten Ainsley Hayes, who then heads off for a snack. He's quite speechless until after she's left, at which point he says "...I could have countered that, but I'd already moved on to other things in my head."

Web Comics

This from Sluggy Freelance.
Here in Skin Horse, Dr Lee doesn't think Tip is an idiot, as such, but she certainly wasn't expecting his pithy assessment of the situation.
Order of the Stick frequently uses this for its punchlines. See here and here (spoilers).
Another Skin Horse example, and again it's Dr Lee that has walked into it.

Western Animation

In Justice League Unlimited Lex Luthor is trying to shut up Tala so he can concentrate on reviving Brainiac. Tala says "Transmutation of matter is what you want, right?" It takes a bit of time for this to sink in, but Lex is finally taken aback. "Do it then!"
Parodied by Peggy in King of the Hill, where she goes on a thirty second rant of how she cannot say anything to that.

PEGGY: Hank Hill, I am speechless. I literally have nothing to say. Not one word. Nada. Zilch. Zero. (beat) I don't know what you're waiting for.

From Regular Show:

Mordecai: But if there is one thing you can trust us with, it's perfecting pointless skills on company time.
Benson: Wow... I really don't have an answer to that.