Neal Whitman wrote a good article at Grammar Girl recently on the possible origins of because as a standalone preposition. This helpful passage from Whitman sets out the context: 
 
 In Standard English, the word “because” can be used two ways. One of them is to introduce a clause, as in “Aardvark was late because he was waiting for the repairman to show up.” Used this way, “because” is a subordinating conjunction. The other is to team up with “of” to form what’s called a compound preposition. For example, “Aardvark was late because of heavy traffic.” In the past three or four years, though, a new usage for “because” has been developing. In July 2012, two linguists independently decided to call it “because NOUN.” On July 2, Laura Bailey called it this in a post on her linguistlaura blog, and on July 12, Mark Liberman independently did the same in a Language Log post. I was just lucky, really…’” 
 
 There’s also an old and standard construction that’s superficially very similar to prepositional because. Buy Now 
 
 But where did this “because NOUN” come from? 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”. A five-year-old chose Toy Story 2, quote, “Because Evil Emperor Zurg!” A four-year-old liked Monster Inc. “Because the day care.” A six-year-old chose Monsters University, “because the part where Sully has the big roar and scares all the policemen.” 
 
 "Because" as a Preposition 
 
 The new usage of “because” treats it as an ordinary preposition, by having it introduce noun phrases instead of clauses or the word “of.” I’ve also heard teenagers say things like, “I’ll do that when school’s out, because more time.” 
 
 This construction got a name just last year. Sure. ), but is currently actually represented by a Democrat lady, which is weird.
– Because politics. Because science. Because money. Remember when you'd need an "of" in these sentences? No longer, because Internet-speak, writes Megan Garber in the Atlantic. In short, the Internet has turned "because" into its own preposition (as language expert Stan Carey has pointed out). For example, the sun's turning upside down, but don't worry, "because science," the UK's Metro notes. Or "skipping lunch today because sleep," says a Twitter user. Or a politician will win "because R-Oklahoma," points out Wonkette. There are a number of theories as to how the "prepositional-because" or "because-noun" began. Memes featured it as far back as 2001 ("because f--- you"). It could be derived from the phrase, "because, hey, (insert noun here)," says linguist Neal Whitman. For instance: The politician will win "because, hey, R-Oklahoma." Or maybe it's tied to parents telling their kids no, just "because." What's clearer is why the "prepositional-because" has taken off: It "maximizes efficiency and irony in equal measure," Garber writes. Click for the full piece.