Self-refuting utterances are obviously false by the very fact of their being made. “I am now asleep”, or “I am not writing this sentence”, or “Words have no meaning”” – are examples of self-refuting statements.
There are some instances in which stating such utterances makes perfect sense, as in being under hypnosis and saying what has been suggested. The context legitimizes the absurdity because the focus is on saying something whether it is bizarre or true or false. Another instance occurs when a description is spoken that matches reality metaphorically, such as “I am floating!”, spoken at a certain point on a real roller-coaster ride. Stated sensations may be examples of self-refuting claims but their verbal expression may be very good literature.
Metaphorical expressions, although self-refuting, may enhance reality enough to make it interesting at least. Watching a boring movie and saying to you friend, “I am asleep”, has contextual correctness.
So humans can communicate falsehoods on a regular basis to achieve status, recognition, or levity, or even clarity when the false statement by way of its impact, makes the situation clearer to those experiencing it.
Finally, those suffering from some sort of mental disorder such as schizophrenia, may speak self-refuting statements regularly, believing them to be absolutely true. Self-deception may lead to self-refuting claims, even among sane people who have a need to exaggerate to gain an edge in an argument or debate.