A black operation or black op is a covert operation typically involving activities that are highly clandestine and often outside of standard military protocol or even against the law.

Black ops missions often fit into the plausible deniability category, 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 – most often – black operations involve extensive arrangements so as to be able to hide the fact that the black operation ever occurred. Black military operations, or paramilitary operations, can be used by various secret services to achieve or attempt to achieve an unusually sensitive goal. The methods used in black operations are also used in unconventional warfare. Depending on the precise situation in a given case, and the level of authoritarianism of the national government or other responsible party, some tasks will be conducted as black operations, while there are usually other activities that can be admitted openly. Black operations may include such things as assassination, sabotage, extortion, spying on allied countries or one's own citizens, kidnapping, supporting resistance movements, torture, use of fraud to obtain funds, use of child soldiers, human experimentation, trafficking in contraband items, and false flag operations, among others.

In the English language, black sheep is an idiom used to describe an odd or disreputable member of a group, especially within a family. The term has typically been given negative implications, implying waywardness. It derived from the atypical and unwanted presence of other black individuals in flocks of white sheep.

In psychology, the black sheep effect refers to the tendency of group members to judge likeable ingroup members more positively and deviant ingroup member more negatively than comparable outgroup members.

The term originated from the occasional black sheep which are born into a flock of white sheep due to a genetic process of recessive traits. Black wool was considered commercially undesirable because it could not be dyed. In 18th and 19th century England, the black color of the sheep was seen as the mark of the devil. In modern usage, the expression has lost some of its negative connotations, though the term is usually given to the member of a group who has certain characteristics or lack thereof deemed undesirable by that group.

PHASE 2 (aka Lonny Wood) is one of the most influential and well known New York City aerosol artists. Mostly active in the 1970s, Phase 2 is generally credited with originating the "bubble letter" style of aerosol writing, also known as "softies". He was also influential in the early hip-hop scene.

Phase 2 is from The Bronx, and attended DeWitt Clinton High School along with a number of other early graffiti artists. Many famous graffiti writers of the early 1970s would meet at a doughnut shop across from the school called the Coffee Shop before heading down to the subway station at 149th Street and Grand Concourse to watch tagged trains on the IRT line pass by. Phase 2 was mentored in graffiti by his friend and neighbor Thomas Lee aka Lee 163d!, one of the pioneers of graf writing in The Bronx.

He began writing in late 1971 under the name Phase 2, a moniker which had a rather mundane provenance. As Phase 2 would later recall, "the previous year we'd given this party. We were getting ready to give another one and I said, 'We'll call this one Phase Two.' I don't know why, but I was stuck on the name. It had meaning for me. I started writing 'Phase 2.'"