It is SO annoying, when involved in a vaguely intelligent discussion with someone, when they begin to engage in verbal gymnastics such that suddenly, even the meaning of words are re-defined, and what should be regarded as questionable assumptions are taken as givens. Mostly I find this happens when talking to theologians or to people with an exaggerated sense of their own moral superiority. When this happened to me the other day I got exasperated and said 'I assumed the world was round, so I went round it, and it was flat, all the way round.'
This is another good response to that sort of person/argument/thing.
Happy Leaping Day