For example, person A states something. Person B says "And pigs fly" to imply person A was wrong.
If there's no term for it, what could you call that that sounds smart?
For example, person A states something. Person B says "And pigs fly" to imply person A was wrong.
If there's no term for it, what could you call that that sounds smart?
To a logician, your examples would be reductio ad absurdum. "If that's true, then I'm a Dutchman/the Queen" is both a well-attested phrase and a valid proposition, implying that whatever it is is false. Similarly, "And pigs fly" asserts the equivalency of what has just been said to a clearly absurd proposition. (Martin Gardner, in The Annotated Snark, traces the phrase to "an old Scottish saying, 'Pigs may fly, but it isn't likely'.")
A general word for such a response is retort, before which you can use a relevant adjective if necessary.
You could call the above, for instance, a sarcastic or witty retort. (Though I think you'd have to do a bit better than "and pigs fly" to merit the word witty.)
Another option is riposte.
I should add that neither retorts nor ripostes need be "false" themselves. They do, however, highlight the falsity or absurdity of what was just said.
This is diasyrmus, which, according to the Silva Rhetoricae definition is "[r]ejecting an argument through ridiculous comparison."
In this case the comparison is implied: person A's statement is as false or absurd as the notion of flying pigs.