The term Men in Black (MIB), in popular culture, is used in UFO conspiracy theories to describe men dressed in black suits, sometimes with glowing eyes or other monstrous features, 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 term has also been adopted as a tongue-in-cheek term in geek culture for any generic suited government/corporate official. _Wikipedia