Blue Meanie cubensis (not to be confused with the "Blue Meanie Pan cyan") are thought to have originated from Australia, where they were collected from the wild and isolated as a distinct strain. They are said to be named after the blue color that appears on their caps and stems when they are bruised or handled, which indicates the presence of psilocybin.
It's also possible that that they were named after a character in the Beatles' visually psychedelic film, “Yellow Submarine”.