Autistics Speaking Day (1 November)

That is, not "austistics speaking" as a phenomenon that might be studied by a linguist, or (God Forbid) "Talk Like an Autistic Day",
but rather autistics speaking to the rest of us, telling us about themselves.
The Day was established by the Autistic Self Advocacy Network in 2010.
Crystal quotes at length from this site:
https://autisticadvocacy.org/about-asan/about-autism/
One point made clearly is that there probably isn't any such single "autistic speaking" that a linguistic could study, since autistic people have a huge range and variety of communicative economies and resources.