shit for brains; dumbass
Strongly derogatory insult for someone acting stupidly or cluelessly. Often used in rough, casual speech or online.
What the hell are you doing, you shit for brains!
That dumbass apparently messed up again.
Common katakana spelling; usually written in kana.
Kanji spelling is rare; the word is usually written in kana.
Compound of クソ (kuso, 'shit') and ボケ (boke, 'fool, idiot'), a dialectal/insulting term from 惚ける (bokeru, 'to be senile, to be foolish').