笨,笨蛋,笨口拙舌,笨头笨脑

笨 = stupid, dull, dumb, foolish, fool, clumsy

笨蛋 = blockhead= dunce= fool = idiot

笨口拙舌 = is clumsy in speaking and slow in speech

笨头笨脑 = slow-minded = dull minded