I have today been into my ds (4) bedroom where he was as said he was tired and he was touching his willy, and had made it big.
I asked him what he was doing in bed and he told me tickling. I just said ok and left not knowing quite what to do.
When he come down i asked him why he did it and if anyone had told him to do it, he told me no one told him to do it and he does not know anyone else who does it, he said he just likes tickling it as it feels nice. I told him he can always talk to me and did not make a big deal out of it.
Oh yes, ds does this - mainly in the bath. He's also discovered that he can retract his foreskin a bit which he's very impressed by.
Unfortunately I got caught on the hop a bit by it so when he said "Mummy look, what's that?" I said "that's your penis" so he thinks when it's big it's called a penis and when it's small it's called his willy...
Will leave the clarification for a while and delegate to dh I think.
Both my DD's (6 & 3) fiddle with themselves. All children do it, as soon as they have the coordination to make their hands go where they want to they invariably find their tickley bits!! We just tell our girls not to do it when there are other people around ie; keep it to the privacy of their bedroom etc.
I think the best thing is to just ignore it, treat it like the natural thing that it is and guide him as to when it's appropriate or not as the case may be.