Mystic Pony Posted in M Best definition Mystic Ponydrugs A slang word for methamphetamine. Used as if one was riding the mystic pony. That guy? Oh yeah, he’s definitely riding the mystic pony. How satisfied are you with the definition? Looking for Mystic Pony meaning? Delighted that you discovered the greatest determine on our web site! Recently this definition was actually observed 19 times.