The term Men in Black (MIB), in popular culture, is used in UFO conspiracy theories to describe men dressed in black suits claiming to be government agents who attempt to harass or threaten UFO witnesses into silence. "All MIB are not necessarily garbed in dark suits," writes American writer Jerome Clark. "The term is a generic one, used to refer to any unusual, threatening or strangely behaved individual whose appearance on the scene can be linked in some fashion with a UFO sighting."
The phenomenon was initially and most frequently reported in the 1950s and 1960s; it is contemporaneous with many other conspiracy theories. According to Clark, the archetypal men in black encounter was alleged to have occurred in 1953, when publisher Albert K. Bender asserted that he'd uncovered the secret behind flying saucers, but had been threatened by three men who wore black suits and hats. Initially, Bender clearly implied the men were U.S. Government agents, but his later accounts blended supernatural features with UFO lore.
The term has also been adopted as a tongue-in-cheek term in geek culture for any generic suited government/corporate official. This usage has its roots in both the popularity of shows such as The X-Files and UFO culture, and the "threat" to hackers of Men in Black actually coming for them (in the form of the FBI or other cybercrime institutions).