I'm thinking of a book I once saw that presented as a non-fiction account of conspiracy theories.
As the book progresses small bits of the book begin to suggest things aren't what they seem. e.g. A numbered list you'd expect to go 1,2,3 but instead had numbers which spelled out a secret message. Something like "They're watching" idk.
More of these "cracks" would begin showing. The books structure would start dissolving and become frenetic. Suddenly, all those hidden messages disappear. The following few pages are completely clean, structured and act like the previous sections didn't exist. In fact the book takes on a completely different layout and typography.
The author can only hold onto this facade for so many pages before all the structure dissolves rapidly and big black ink scrawlings cover the pages. I recall it was something like
"HAHAHA" and "DEMONS" over and over again. edit: Also a picture of a UFO
It's a tough one. I think I saw it on DeviantArt? Any help is appreciated <3