Susan lives in the fictional country of Lieber, which raises government revenue by taxing everyone the same amount. The government of Lieber has just implemented a tax cut that reduces annual taxes by $2,000 per person. However, government spending has not changed, nor is it likely change in the future. The tax cut has raised Susan's income by $2,000. If Susan acts according to the prediction of new classical economics (and doesn't plan to leave Lieber), her saving is likely to increase by.
Suppose that instead of cutting taxes while keeping its spending the same, the government did the oppo it increased its spending by $2,000 per person while keeping taxes the same. If everyone in Lieber acted like Karen, the likely increase in aggregate demand would beper person.