Hanapin
to foul one's (own) nest
01
to behave in a way that damages or undermines one's own reputation or success
The idiom "foul one's own nest" has its origins in the behavior of birds who will dirty their own nests with excrement or waste. The phrase is now used in a more figurative sense to describe someone who is behaving in a way that is damaging or harmful to their own reputation or interests. The usage of the idiom is not limited to any particular context and can be applied to a variety of situations where someone is harming themselves or others by their behavior.
Halimbawa
The country's excessive military spending has fouled its own nest by bankrupting the economy and leaving little funds for infrastructure and social programs.
The company fouled its own nest by releasing toxic chemicals into the local environment, alienating the very community it depended on for workers and customers.
The business owner who mistreated their employees was a reminder that it is an ill bird that fouls its own nest, as their actions ultimately led to high turnover rates and damaged their own business.
By treating his employees poorly, the manager has fouled his own nest by creating an unhappy and unproductive workplace.