Answer: Swift uses verbal irony when he calls his friend a “patriot”; a true patriot would not suggest using Ireland’s children for food.
Verbal irony refers to a situation in which the speaker says something which is the opposite of the truth. It is a very common and useful rhetorical device. In this case, Swift describes his friend as a "patriot." However, a patriot is a person who cares deeply about his country, and the friend, instead, wants the children of Ireland killed and eaten. He is, in fact, the opposite of a patriot as he does not care about the well-being of the Irish citizens.