Over on The Thinking Person's Guide to Autism, there's a very interesting post about interaction badges.
This is basically a means of coding the 'please engage/avoid me' message which is usually relayed through a complicated dance of body language and neurotypical telepathy. There are three badges - red, yellow and green - with meanings vaguely related to the symbolism we're used to associating with those colours through traffic lights.
Red means 'do not initiate interaction with me'. That doesn't mean 'ignore me if I talk to you', but it's a sign not to barge on up and start yapping. If the world at large understood interaction badges, I'd put one of these on when I'm clothes shopping. It's a situation where I feel weird and awkward and self-conscious - plus usually a bit overstimulated from the instore radio and all the other people - and being left alone to do my thing would be best for all concerned.
Yellow, in autistic circles, means 'only interact with me if I already know you'. I personally wouldn't have a lot of use for this one, but if it's specifically strangers that send you running to hide in the bathroom, this could be a hit. Actually, I'd like one that says 'I know you know me, but I'm not up for a chat right now, ktxbai' to wear while grocery shopping. But I guess that's what the red one's for.
Green is the one I'd wear the most, if these were a thing in the wider world. It means 'I'd like to interact, but have trouble. Please talk to me!' This is kind of the story of my life - most times I would have loved to have had a friend, an acquaintance, a playmate, but because I come across as 'wrong' or 'off', it just doesn't happen.
I actually think interaction badges have a practical application much further afield than the autistic community. Jenny Lawson, AKA The Bloggess, has written about her anxiety disorder, and how it tends to leave her trapped in bathrooms at social shindigs. And how many times have we - the general we, as in everybody ever - been told 'don't be shy.. the person you're talking to is just as nervous as you are!'? Well, now we can tell, empirically, if that is the case.
Or if they want us to sod off.