A Black Operation or Black Op is a covert operation typically involving activities that are highly secret due to questionable ethics and legality. The term itself is often used in political, military, intelligence and business circles. Agents or persons who specialize or are involved in a black operation are typically referred to as a "Black Operator" or "Black Operative".
Black Ops missions often fall into the deniable category, a situation in which there is no claim of responsibility for the action, and/or a false flag operation is used to give the appearance that another actor was responsible, or... involve extensive arrangements so as to be able to hide the fact that the black operation ever occurred.wiki
If you're part of a super-secret, clandestine, covert military unit, it seems like you wouldn't want to advertise it.
Turns out, some "black ops" personnel do. They come up with cryptic designs - images like dragons wrapped around the earth or naked women riding killer whales - to put on patches that commemorate their missions. What they mean and the details of the missions are almost impossible to figure out.patches