Men in Black
A popular term for putative aliens or government agents who allegedly visit UFO witnesses and warn them to keep quiet.
Men in Black was a hoax perpetrated by Gray Barker, head of Saucerian Publications, in his plausible–but fictional–They Knew Too Much About Flying Saucers (1956). The M.I.B. were said to favour older model dark GM cars, didn’t like to be photographed, and dressed in black.
In response to the anticipated question, “How is this relevant to medicine?”, paranormal phenomena–e.g., miraculous cures defy explanation and pit belief against science. Most doctors don’t believe in creation science, aliens and miracles, but are loath to shatter faith with cold hard facts, as faith is tied to hope, patients’ will to live and acceptance of death.