The Vietnamese word "càu cạu" is an adjective used to describe someone who looks glowering or surly. It often refers to a person's facial expression or demeanor that appears grumpy, irritated, or displeased.
Mặt của anh ấy hôm nay trông càu cạu.
(His face looks glowering today.)
Cô ấy luôn càu cạu khi không được ngủ đủ giấc.
(She is always surly when she doesn't get enough sleep.)
In summary, "càu cạu" is a descriptive word for someone who appears unhappy or grumpy.