giddy I completely sympathise with you post and understand what you did and why it worked. All that has shocked me on this thread is a professional suggesting that I deliberately hurt him back because it is usually the last thing they would sanction. Partly because of that risk of frustration spiralling. It is also something that I know ds1's teachers would never do, and I know they would help me avoid it.
I'm sure if you came into our house mizmiz you woulsd recognise it as belonging to an autistic child. There are locks everywhere, scribbles on the wall and furniture that is falling to pieces. Partly because we've spent all our money on therapy (no more - we ran out and anyway he's in a great school now), and partly because I mind more if he poos on a new floor, or draws on an new wall than an old one. We still teach him acceptable behaviour (or try to) but in an environment that is more ameniable to lapses. I aim to do the house up in about 5 years as by then I suspect he'll be less trashy, and we'll have more money. Ds1's private SALT (who taught in an ASD school) used to say she was impressed that I was able to remain calm and kind of detach myself from it all- I replied something along the lines of "well you have to don't you" and she said that some couldn't - her inference being that thier mental health suffered. I don't try and give any sembence of normality, but not because I've given up, but because that would be living a lie and would be too stressful, and impossible to maintain.
As Davros says - yes he knows its naughty- which is why he does it. But not because he's trying to be "bad", because he knows naughty things get people riled. He doesn't understand naughtyness in the way that his 3 year old brother does. He doesn't do naughty things because he is generally obedient (god help us if ds3 is autistic, he's far more willfull), but he does findit highly amusing to be naughty if he's feeling mischievous. For example sometimes when we walk down the steet he'll start to giggle like crazy, and I know that he's going to either press someone's doorbell, or press a pelican crossing button or dive into an estate agents. All things that he knows are naughty and therefore = fun. To him pinching is the same as pressing someone's doorbel. Fun to do if you are bored, or feeling a bit mischeivous. For a while he drove his teacher up the wall because every time he turned the computer on in the classroom ds1 turned it off, to a fit of giggles.
Davros I think you are right- he is doing it for attention. Like your DS he is faiirly sociable despite being screamingly autistic, and likes little games.
Anyway the good news is I seem to have found saomwething that works at the moment. I was lying down on the sofa (feeling a bit grotty today - virus I think) and he came to join me as he usually does. I found that if he went to pinch me a bored sounding "hands down", or "no pinching" or " you'll go outside the room" worked. As I said yesterday in response to a post by Davros - verbal instructions appear to often work better with him. He's now pretneding to pinch me 90% of the time, rather than actually pinching. IN the meantime he was happy to play round and round the garden and wanted me to read James and the Giant peach to him (WTF???) Anyway the point is now I'm not being lunged at continuously I can get close enough to him to redirect and do something else (even if it is only round and round the garden).