Irony: a statement in which the implicit meaning of the words differs the explicit use of those words.
When Elijah says to the prophets of Baal on Mt. Carmel, "Cry aloud! Surely he is a god; either he is meditating, or he has wandered away, or he is on a journey, or perhaps he is asleep and must be awakened" (I Kings 18:27), he is being ironic—he does not believe their gods are gods at all, and they will not pass the test.
The danger of irony is that it will be missed. ...To be able to find irony in a text, the reader must be able to trust what is said and to discern a reason why what is said is not what is intended.
Patzia & Petrotta, Pocket Dictionary of Biblical Studies (2002), 64.