WARNING; The following text contains rambling ravings. Sensitive viewers may wish to switch to another message thread.
About 20 years ago this became one of my pet peeves, as in: Who the @#%&! do you think you are to command anyone to behave differently? This was 20 years before my AS diagnosis, and I already had a vague, subconscious resentment of being expected to try to fit into a world I didn't understand or feel comfortable in. What really pushed my buttons about the "Smile!" command was the speakers' casual, joking, offhand manner. They weren't taking me seriously. They weren't respecting my feelings. And worst of all, I eventually concluded that the reason they said it was because they didn't understand or feel comfortable around ME. Their social skills were so simplistic, narrow-minded and intolerant that they couldn't relate to me, so they tried to force me to behave in a way they could relate to, without even considering whether I wanted to, or how difficult it might be, or at least that I might have good reason to look depressed or preoccupied.
So I would get prickly-defensive and say "If my face offends you, I suggest you avoid looking at it." I don't think they got the message though, so I have since switched to "This IS my smile" in a dismissive deadpan, although just once I'd like to try telling someone "My mother died yesterday. Any more questions?"
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"the largest disability... [for those with AS] is the inability of non-autistic culture to accommodate their differences in respectful, empowering, and constructive ways" -- Donna Williams