It might be that no one can help with thi9s, but it's worth a try.
Some of you may recall i mind a 3.6 year old and his 18 month old brother. Well just recently the 3 year old has started displying what i would term "inappropriate behaviour". I had noticed him doing it once or twice previously but not to the extent that he is now.
He stands/sits/leans against anyone who is near us and strokes them - their hair, legs, arms and sometimes chest! He did it to my DH yesterday and he ended up going off in the car for a couple fo hours to get away, even if he moved away the little one would follow. He does it to my friends when they pop in with their children, he does it other mothers at toddler group and if we are standing near someone at school he strokes their leg. The whole time he is doing it he has what i can only describe as a "manic looking " grin. He also shoves his brother and the other mindee i have. If he is, for example, walking across the living room, and his brother is in his way,he won't go round him, he will shove him over and step on him to get to where he is going, same if there is a toy in his way he will just step on it, he doesn't seem to be able to grasp the fact that he should go round it. he repeats himself over and over until i change the subject. EG "what you doing Saltire" so I tell him, then he says it again, so i tell him again, etc etc. I mentioned all this to his parents but they never said anything, just "Oh yes he does this at home". How can i stop him from touching people? It's got to the stage where i am going to have to stop going to M&T's as the other mums are getting uncomfortable.