The phrase "angry cat" is a common expression used to describe a cat that appears agitated, irritated or upset. This could be due to various reasons such as being startled by something unexpected, feeling threatened or in pain, or simply not wanting to do what it's being asked to do. When someone says "angry cat," they are usually referring to the cat's body language and behavior which may include hissing, growling, swiping with its claws, arching its back, flattening its ears, and making a low rumbling sound in its throat. The phrase is often used humorously or figuratively to describe someone who is behaving similarly to an angry cat - showing signs of irritation or annoyance.