We all know of the subs like "You Should Know," but what something you SHOULDN'T know?

There are some atrocious actions people have done to other people and themselves that I wish I could unlearn. Not just the genocides, slavery, and mass rapes across history and currently but the individual stuff like what happened to Furuta Junko (nsfl). I used to think learning about the more morbid nature of humanity would be helpful to understand but it’s hard not to become cynical or misanthropic after learning about some of the worst stuff.