I haven't ever heard that term used when people were referring to mentally ill. Rather, it is more commonly used to describe a person who is cognitively challenged. Mental retardation, severe autism, and those types of disabilities.

It has always bothered me ~ as a cousin of mine has moderate/severe retardation, and it personally hurts me as the word is often said in the opposite emotion, with a sigh and rolling the eyes. There's still a lot of discrimination and negative statements made about those cognitively disabled, people just aren't as bold as they used to be.

If people are lumping you into that same category, I'd be hurt and angry as well. While most people are unaware of my cognitive disabilities, I'm not bold enough to speak up when remarks are made & stand up fo myself (and others like me). Gentle hugs to you!