to be unable to make any sense of the matter/to be at a loss
Related Sentences
丈二的和尚——摸不着头脑 ( Monk of the second husband-scratching his head )
明明对方犯规，却对我出示红牌，那裁判的判罚真让人丈二的和尚——摸不着头脑！ ( Obviously the opponent fouled, but showed me a red card, and the referee's punishment really made the second monk-scratching his head! )