Stan Carey lays out an interpretation of the recent origin of using “because” as a preposition:
Neal Whitman agrees with Language Log commenters who think it could be from “Because hey”–type sentences (If life gives you lemons, keep them, because, hey, free lemons), where hey functions “like an adaptor, letting you shift from the ordinary speech register to this casual and condensed register”. And then people started dropping the hey. It’s not always hey, either: take this line from the linguistically trend-setting Buffy, season 5 (January 2001): “I don’t even get how we made that guy, because, wow, advanced!” There may also be forerunners in child–parent exchanges like “Why? That’s the why” and “Why? Because.”; and in the popular insults “Because shut up” and “Because fuck you, that’s why.”
But Gretchen McCulloch isn’t so sure about Whitman’s explanation:
I’m skeptical about Neal’s “because, hey” explanation, because as I noted last year, we don’t see a lot of instances of “because noun” with any sort of additional modifier: the most canonical instances of “because noun” are with a bare noun, not a noun phrase. So, “my mouth is sore because lemons” sounds fine to me, but “my mouth is sore because free lemons” sounds a bit more marginal. Not totally unacceptable, maybe, but not the core upon which “because noun” was founded. (Stan Carey‘s examples have only 4/19 with more than a single word after “because”.)
In contrast, the modifier is crucial to the humour of the “because, hey” expression, and “because, hey” just doesn’t work in all the contexts where we find “because noun”. For example, something like “If life gives you lemons, keep them, because, hey, lemons” only works if the person you’re talking to already knows the joke or sees the value in lemons. And the example above, “my mouth is sore because, hey, lemons”, is just plain weird. The “hey” implies that the lemons are good, but the previous part of the sentence is saying that the lemons are bad, so I’m really not sure what someone could mean by saying this.
Megan Garber’s take:
However it originated … the usage of “because-noun” (and of “because-adjective” and “because-gerund”) is one of those distinctly of-the-Internet, by-the-Internet movements of language. It conveys focus (linguist Gretchen McCulloch: “It means something like ‘I’m so busy being totally absorbed by X that I don’t need to explain further, and you should know about this because it’s a completely valid incredibly important thing to be doing'”). It conveys brevity (Carey: “It has a snappy, jocular feel, with a syntactic jolt that allows long explanations to be forgone”).
But it also conveys a certain universality. When I say, for example, “The talks broke down because politics,” I’m not just describing a circumstance. I’m also describing a category. I’m making grand and yet ironized claims, announcing a situation and commenting on that situation at the same time. I’m offering an explanation and rolling my eyes—and I’m able to do it with one little word. Because variety. Because Internet. Because language.
(Image of “Because Racecar,” the inaugural “Because X” meme, via KnowYourMeme)