|“||Aww, man. Looks like I gotta find some new reading material.||”|
Donut's Diary is a diary that appeared in "The Liar Ball You Don't Want". It has the same cover as Creatures of Goiky, suggesting that they are the same book, both the same blue color with the same odd symbols. The only difference between the books being the picture of Donut in the yellow oval in Donut's Diary. As the name implies, it is a book owned by Donut expressing his thoughts and findings. It was in the possession of Loser inside the Liar Ball until "The Escape from Four". As of "Return of the Rocket Ship", there appear to be sticky notes in some of the pages, as Loser must be taking note of some of the interesting finds in the diary.
The second copy of Donut's Diary was seen in "The Escape from Four". However, it is cyan and has the number two in roman numerals next to Donut on the emblem on the front cover.
- "Dear Diary, I regret to inform you that I discovered something very horrific about Bomby today. You see, he—"
- "Why do I have filling, but also a hole?"
- (Cryptic message) (What it says is unknown, but in "Get to the Top in 500 Steps", Loser says "Wait, is that some kind of cryptic message?")
- "Dear Diary, today I experienced a feeling I never imagined possible. I felt myself combine with the factor of four. Becoming a number revealed so much to me. I learned what's really inside the speaker box. It contains...It contains... Well, it's getting late. I’ll tell you tomorrow Diary."
In "The Escape from Four", the second diary is briefly shown when Loser grabs it from Donut, stating that he "needed new reading material".
In "Lo-Fi Beats to Yoyle To — BFB 21 on Friday, July 3", Donut was seen writing in his diary and listening to some music.
- Donut's Diary's color was changed to be much lighter in "Who Stole Donut's Diary?".
- Donut's Diary (II) got ripped apart by Four in "Who Stole Donut's Diary?".
- Taco's piece of Donut's Diary (II) contains at least 58 pages.
- Donut's Diary (I) may have been left in the E.X.I.T.
- Donut's Diary looks identical to the book in "BFDI Is Back".