Where is this is heading and why didnt I stop the train before it flew off the tracks

Actual conversation between my 23 month old son and I:

"Vivi have penis!"
"No, sweetie, Vivi doesn't have a penis."
"Vivi have penis!"
"Actually, Vivi has a vagina."
"Vivi have (unitelligible stutterings) penis eh eh um mangina!"
"Yes, Vivi has a VAGINA (enunciating clearly for him. He's almost two, he should be able to say it correctly)
"Aga have magina!"
"No, bug, Isaac has a penis. Boys have penises. Girls have vaginas" (Wonder, is penises really the plural of penis? Or should it be peni?)
"Daddy have penis! Aga have penis!'
"Yes, yes, you are right. Lets go get some milk, okay?"
"Penis!"

So, is this really what I want to be discussing with my son? Shouldnt I have just changed the subject (you know, by redirecting him) when it first came up? The correct answer to those two questions: No, and, yes. And I'll tell you why.

That is the exact same conversation I had with him at EVERY SINGLE DIAPER CHANGE today. In case you dont have a 23 month old--that is approximately 8 times a day--on a good day. It is also the same conversation I had with him every time he saw me changing his 7 month old sister's diaper today. (For the uninitiated, approximately 10 times).

The good news is that this conversation has not migrated from the changing table--yet. I'm sure the next time I'm in the grocery store, or the mall, or some other very public place, he will be loudly insisting that I have a penis for all the world to hear. Ah, anticipation . . .