Boys always will be boys, no matter of their chronological age
I guess we all understand the jellyfish incident a lot better
now boomerang, nonetheless using the word penis for his
penis is probably a better choice, and I agree with you that
a little biology lesson is even for a four year old a good idea.
As always boomerang, you know all the answers yourself,
you just need a bit reassurance - that's all !
sozobe