A statement that means the opposite of its literal meaning, often used for effect.
His 'thank you' was ironic.
rhetorical question
A question asked not to get an answer but to make a point or produce an effect.
'Who would do such a thing?' is an example of a rhetorical question.
ironic; rhetorically ironic
From 反 (はん, 'anti-') + 語 (ご, 'word, language').