A mystical being of tiny proportions that visits a sleeping person in their dreams; it is said to be a little fluffy white unicorn that has a very horny horn upon its head and in between its hind legs. The unicorn is known to ejaculate from both of its horns as it begins to sing the first few verses of 'Hotel California' ... ‘On a dark desert highway, cool wind in my hair…’ Individuals that are visited by The Little Unicorn begin to wander the Earth in search of it's mystical Lord for the rest of their lives, following the motto that they themselves are "A Little Unicorn".
Once I was visited by The Little Unicorn my eyes were opened to reality.
Suggesting this is a way of saying someone is talking or acting crazy. Used to express disbelief, skepticism, or simple mocking. Indicates a level of ridicule serious enough to move the subject away from what the other person has said, and onto the state of mind of the speaker.
"If you think you can get away with driving 50 more miles with the 'Empty' light on, you need a checkup from the neck up."