Re: Incorrigible 3-year old
I agree with Misty. Also, do not believe everything your preschool is telling you. If you have friends that don't want to hang with you because of your son's behaviour, it's a good bet he also does this at school too. Perhaps they have a way of dealing with it that actually works for your son. Can you observe without him knowing you are there?
Also, I believe in consistency. It sure sounds like you're trying everything, but are you trying everything a zillion times a day? You say he does the bad behaviour right after being scolded for it. Keep at your calm, firm discipline, use one or two methods and DO NOT deviate. If you want time outs as your tool, then really work it. Get a chair or whatever, away form ALL toys, distractions and he needs to sit there the entire time, no talking, no yelling, no tantrum. You stay calm and do not speak to him other than the first time you put him in time out.
We also have a method for extreme bad behaviour for home or while we're out in public. Whatever child is acting up has to hold one parent's hand. We tell them they have to do so until they are under control and behaving properly. They will resist of course and pull, tug and cry more than likely, but it does work. In public, we will go off to a corner or whatever so we're not disturbing other people but if we're in a loud place, like a mall, they hold our hands and we go about our errands. It only takes a few times and they realize it's nicer to be nice! My kids now are to the point where I'll hear one of the older ones say "Mom's going to make you hold hands, come on, be good."
Our big thing is we always calmly, but firmly tell them what they are doing is unacceptable and what the consequence is then follow through. It's sure easy to give in, but do your best to stay strong! I've found boys go through this 2 to 5 year old stage that can be horrendous. Hang in there.