鸡不如人
[jī bù rú rén]
The term "Chicken (ji) isn't as good as people" may sound strange to non-Chinese speakers. In Mandarin, "鸡" can also refer colloquially to a person who is not very competent or capable. Thus, the nickname suggests that someone sees themself or someone else with a low level of competence and perhaps even self-deprecating humor.