KnifeMissile

This is called a double negative and a lot of people have trouble with it, even when it's done intentionally. For instance, a lot of people will be confused by a sentence like "I haven't had no luck with the post office."
It's not even necessarily their fault. A common English protocol is to ignore the negative, like in the question "Don't you like it?" If they do like it, their answer is typically "yes," even though the question asked the opposite. So, if the question was "Do you like it?" and the answer is "Yes," then the answer to "Don't you like it?" should really be "No." This problem seems to be specific to English, too. For instance, the Japanese, have no problems with their inversions or their double negatives.

Another one (although I've already said this but it's a long thread and, already, people have been skipping the middle parts to read the end) that's similar to this is the use of "by definition." "By definition, women should stay at home." Really? The definition of a woman is someone who stays at home?
Although one might be generous and just call these misuses "exaggerations" but I honestly think they're born out of ignorance. If you don't realize you're "exaggerating," can you really be exaggerating? It doesn't mean this literally by definition but "close" to it? I don't mean literally literally but close to it?