Hyperbole, like exaggeration, is a euphemism for a lie; it is a common and socially accepted lie, but it is still a lie. If you catch someone lying about something, wouldn't you worry about whether he was lying about something else that you were less informed about? I admit neurotypicals don't seem to care much about lying, probably because you can't seem to help yourselves, but some of us do care.
So if I said to you that my laptop "weighs a ton", it will diminish my credibility with you simply because its mass is not literally 2000 pounds? That seems rather cynical, or at least uncharitable.
Deliberate hyperbole is not a "lie" in any sense of the word I understand, because it is not designed to deceive anyone. It's generally done as an expression of hand waving. You are being deliberately imprecise, either because you genuinely don't know the real value (in which case "guessing" would be presenting a deceptive level of precision which you do not actually have), or for humorous effect - to make a point more emphatically.
The laptop example used below is good. Saying "this weighs a ton!" is much less deceptive than if I took a guess and said "this weighs 2 kilograms". It obviously doesn't weigh a ton, because its density would probably exceed that of all known elements. Saying it weighs a ton has two connotations: 1) That I don't know how much it weighs (or it is irrelevant to the conversation) and 2) I am finding it difficulty to carry because its weight is beyond that which I can carry comfortably. Saying "this weighs 2 kilograms" does not convey the same information.
Similarly, making an overstatement like "Gimp's UI makes me go blind" is clearly not designed to deceive anyone. It is physically impossible that Gimp's UI would have made a person go blind. The person saying this is not asking you to believe it, instead, he is saying "I find Gimp's UI very visually unappealing, and the reasons for this are not important right now).
So, in summary, hyperbole is not the same as lying. Lying is not "anything that is untrue", lying is deception, and the suggestion of deliberate deception where none exists is quite offense to most people!
It seems like there are two conditions that must be met for something to be a lie: there must be a falsehood and that falsehood must be presented with the intent to deceive. Hyperbole, exaggeration and sarcasm may, strictly speaking, be falsehoods, but the intent is clearly not to deceive.
