Psycho Doughboy is one of the Doughboys that act as two of Johnny's inner voices. He is based on the mascots for a certain company (Pillsbury). Johnny admits at one point to stealing him. According to the Director's Cut, he was given a paint job by Nny.
Psycho DoughBoy appears to represent the depressed, self-loathing aspect of Nny's insanity, encourages Nny to kill himself on several occasions. D-boy is continually infuriated with Nny's failure to commit suicide, and accuses him of sabotaging his attempts on purpose. He hates Mr. Eff and constantly fights with him over what Johnny should do with his insanity. Although The Wall Monster is consistently feeding him and Mr. Eff energy to make them more real, he does not wish to become fully real (unlike Mr. Eff) and only wants to serve his master. Eventually, when Johnny accidentally kills himself and The Wall Monster escapes, he becomes happy and proud of his accomplishment. Subsequently, along with Mr. Eff, he is decapitated by The Wall Monster (much to his delight). Johnny later -re-kills him after realizing he was being manipulated by Psycho and Eff.
Oddly, his chest has the word "Fuck" on it and not Mr. Eff.