Definition
An emphatic expression used to indicate that one has absolutely no idea.
我可不知道
"Whose book is this?" "I'll be hanged if I know!"
「这是谁的书？」「我完全不知道！」
"Why did he resign?" "I'll be hanged if I know!"
「他为什么辞职？」「我完全不知道！」
"Where on earth is she going?" "I'll be hanged if I know!"
「她到底要去哪里？」「我完全不知道！」