UPDATED: After a little digging around, Complex can report the beginnings of this thing: Internet message board community 4Chan's notoriously mischievous "/b" board, who created the meme and spent today spreading it around Twitter. See below for proof:
The origins are fake, but the Tweet trending—and the people supporting it—are disturbingly real. The link to the 4Chan board discussing spreading #Cutting4Bieber as a meme is—like most things on /B—very NSFW, but it's here if you want to see the rest. If you're curious as to who and what 4Chan's /B board is, Slate's got a great explainer.
For the record, this isn't not the first time that the highest tiers of Internet Trolls have tried to mess with Bieber's fan base. Late last year, an elaborate prank was mounted in order to convince the world that Bieber had cancer, thus getting his fans to shave their heads in support.