The most important lesson here, is that when you realize that the person is asking for X when they wanted Y, make sure to somehow say something critical, sarcas

The most important lesson here, is that when you realize that the person is asking for X when they wanted Y, make sure to somehow say something critical, sarcastic, or dismissive. That way along with a bit of knowledge that helps them for a moment, you are also delivering a blow to their self-confidence, that will be a detriment for the rest of the day (or, if they were already lacking in confidence, perhaps many days). This may not work on veteran co-workers, but it will work especially well with anyone lacking experience or suffering from Imposter Syndrome.