<span class="chinese-post-title">假癡不癲</span> Feign Madness But Keep Your Balance from the <span class="chinese-post-title">三十六計</span> Thirty-Six Stratagems

假癡不癲

寧偽作不知不為，不偽作假知妄為；靜不露機，雲雷屯也。

"Hide behind the mask of a fool, a drunk, or a madman to create confusion about your intentions and motivations. Lure your opponent into underestimating your ability until, overconfident, he drops his guard. Then you may attack."

Quoted from Chinese Classics and Translations