This is going to sound hard to believe, but...
...based on zero evidence, a bunch of alt-right types decided that a pizza shop in Washington was somehow the center of some sort of bizarre satanic pedophilia cult/ring/thing, and that further that Clinton was somehow involved.
It evolved into some sort of weird meme/circlejerk/echo chamber/witchhunt/circus, centered around /r/pizzagate, complete with doxxing, stalking, physical protesters outside the shop, trending twitter hashtags, all sorts of madness
Unsurprisingly, the sub was banned. And if you choose to ban a sub focused around uncovering (I can't believe I'm writing this) Clinton's pedophile sex ring, then obviously this is because you yourself are a pedophile (and probably a Clinton supporter, which is probably worse). Why else would you help coverup Clinton's satanic pedophile sex cult?
(If you're curious, the original spark behind all this is Wikileak's release of John Podesta's emails. In them he mentioned eating pizza there. Which is clearly code for child abuse, and Podesta is sort of close to Clinton, so Podesta eating pizza is literally Clinton abusing children. No, I'm not making this up, and yes, that's the sum total of the evidence behind this. Literally, the whole thing is based on the supposition that it's so unlikely that Podesta likes pizza that it must be a codeword for child abuse, because obviously child abuse is much more understandable than liking pizza, or something.)