I haven't (though, I tend to internalize my feelings, which causes a host of other problems, and when I do have meltdowns, they're in the house, typically in isolation). My sister, who's 16 and classically autistic, has. One of the most memorable times was when the family went to see The Dark Knight. She's used to sitting in the very front row, keeping several seats to herself in case she wants to lie down. Anyway, it was too crowded and she didn't get to sit all by herself, so she had a meltdown at the theater. My parents decided to take her home, and I guess with all the screaming and resisting, someone thought she was being kidnapped, and called the cops. After being on the road for a few moments, it came to my parents' realization that they were being followed (by the woman who called the cops), and then five cop cars surrounded them. Luckily, upon learning of the misunderstanding, they just talked to my sister.
Then there are neighbors who call the cops simply because my sister is walking around the neighborhood on the sidewalk, and the cops come to our door to report the legendary sighting of The Wandering Autistic. These people don't bother contacting my parents or anything beforehand. I suppose autistic people don't deserve basic freedoms like walking in their own neighborhood!