CAN SOMEONE PLEASE EXPLAIN THE FOREST FIC TO ME?

I was stalking the joshler tag on tumblr and there was a fic called Stay in Place (sing a chorus ) or "the forest fic" and I didn't understand all the references to it so I looked it up and it screwed me up bad. I'm now having an existential crisis on my stairs while my friend watches Pretty Little Liars, stalks people on instagram and yells at me to shut up because I'm mumbling about how bad that fic screwed me up