A favourite I collected from a boss I had for a few years that I'm sure everyone has either heard or uttered:<p><i>For all intensive purposes</i><p>Note: The correct phrase is "for all intents and purposes".<p>Another of my all time favourites is when the literal meaning is precisely the opposite of the intent, eg.<p><i>I could care less about X</i><p>I literally mean: I could care less about the welfare of my children. But then I don't think I actually could care less, as in I can't but care, however in that case then this would also be true:<p><i>I couldn't care less about the welfare of my children</i> (I just couldn't!)<p>Interesting conundrum.