One of my favourite webcomics, xkcd, frequently picks up language-related topics, which is hardly surprising, since it is described as "a webcomic of romance, math, and language". A recent one spoke to the fact that syntactic elements of an utterance can be created completely anew by reassigning a new syntactic role to elements that are normally used differently. In other words, "legit" in this case is used as an adverb although it actually is an adjective, or, more interestingly, "adverbed" is used as a verb when it is usually known as a noun.

Technically, one could accuse Megan, xkcd's female protagonist, as simply getting her language wrong. However, the fact that we implicitly understand what she's saying although it is extremely likely that we've never heard this specific sentence before, is one of the (many!) fascinating properties of human language. (Good ol' Chomsky, coincidentally, shares this view with me when he says, "The most striking aspect of linguistic competence is what we may call the 'creativity of language,' that is, the speaker's ability to produce new sentences, sentences that are immediately understood by other speakers although they bear no physical resemblance to sentences which are 'familiar.'") The way specific words are used, then, continuously changes, and as we integrate more phrases into our daily parlance, our vocabulary can be expanded infinitely. (Sadly, this flexibility can also be abused.) So next time somebody accuses you of using a word in the wrong form, blame it on your linguistic creativity--but make sure to have a valid explanation up your sleeve.