Oral Hygiene Bro
A user of 4chan's /a/ board, who, starting October 2010, started writing a story where he was inspired to brush his little sister's teeth after watching Nisemonogatari's infamous toothbrush scene. Eventually, it got to the point that they married and had a child together. He kept posting for about 3 years, until August 2013, when he was never heard from again. Nobody knows if the story is real, but nobody can prove that it's false either.
Aidan: "yo have you heard of that one Oral Hygiene Bro who fucked his sister"
Bob: "Yeah that's some messed up shit"
Bob: "Yeah that's some messed up shit"