Definition & Meaning of "shitbrain"in English

What is the origin of the term "shitbrain" and how is it used?

"Shitbrain" is a slang insult that likely appeared in English in the late 20th century, formed by combining "shit" (signifying worthlessness, incompetence, or contempt) with "brain" (referring to intellect) to label someone as stupid, slow-witted, or incapable of thinking clearly. The term emphasizes mental inadequacy in a blunt, vulgar way. It is used in informal speech, online discussions, and casual arguments to express frustration, ridicule, or strong disapproval of someone's thinking or decisions. The word is clearly derogatory and offensive, intended to insult rather than amuse.