A "black job" generally refers to work that is done secretly, often involving activities that are illegal, unethical, or not officially sanctioned. This term can apply to various contexts, including espionage, where covert operations or intelligence gathering activities might be described as "black ops" or "black jobs." In the corporate or political world, it might refer to under-the-table deals, off-the-books work, or other activities meant to avoid scrutiny and regulation.
In a different context, such as within the labor market, "black job" can also refer to informal employment or work that is not reported to the government for tax purposes, also known as "black market" labor. This includes jobs where workers are paid under the table and do not receive official benefits or protections.