My ds is a well adjusted boy, happy & sociable but he has a best friend who has just introduced him to the bums and willies game!! intially they just rubbed tummy's then progressed to showing each other there willies and bums and now have started pulling and toucing each other! I dont feel comfortable with this,they seem to know it is wrong from they way they re-act if i walk in on them. Is this normal are they just exploring and natural curiosty or at 3.5 yrs is this a step to far, any advise on how to discourage this and am i overreacting?