Yes, the phrase ‘This place is a zoo’ is indeed an idiom. It is used to describe a situation or place that is chaotic, noisy, and disorganized, much like how one might imagine a zoo to be. The phrase draws a comparison between the unpredictable and often wild behavior of animals in a zoo and the chaotic environment being described.
For example, if someone walks into a very busy and noisy office, they might say, ‘This place is a zoo!’ to convey how hectic and disordered the environment feels. The idiom is a vivid way to express that the situation is out of control or very busy.