What's This?

I am willing to bet that anyone who has had kids or been around kids have had to answer questions that they really didn't want to answer. Here is the conversation Trey and I had after bath time. --- why are kids so inquisitive anyway?

I was drying Trey off and he was lying on the bath rug squirming around like crazy. He was up and down and side to side at least a hundred times in a few minutes. He finally landed, spread eagle in front of me.
"What's this?" he asked pointing down towards his privates.
"You know what that is." I said, "Its your peni". I don't make a big deal out of these questions. He usually doesn't dwell on things if I seem uninterested.
"No....not my peni.....this thing!?!" He exclaimed, pulling on himself.
Oh boy....what to say??? I didn't want to use slang and I couldn't think of anything else acceptable to say. So, remaining uninterested I replied.
"Oh, that's your scrotum."
Trey cracked up. I smiled inside that he found that word so amusing, but I kept a straight face while he giggled.
"Scrotum?!?" He laughed, "I never heard of that before!"
I didn't answer because I wanted the conversation to be over.
But, it wasn't.
"What's it for?" Trey asked.
Ugh...what's it for? What's it for? How is a good way to explain that?
"Uhhh....Ummm....." was all I seemed to be able to get out. I was drawing a blank.
Trey had his thoughtful look on.
"I know Mommy! Its for... to keep my peni from being lonely!"
I nodded. Sure. Why not? That made good enough sense to me. I relaxed a little. That wasn't so bad after all.
"Do you have a scrotum, Mommy?" Trey asked a short time later.
Yikes! He is still thinking about this.
"No, only boys have those" was my answer.
"So, Daddy has a scrotum?"
Good grief! I've got to get this kid to bed so he'll stop asking questions!
"Yes" I answered.
"Where does Daddy keep his?" Trey asked.
I was biting the bottom of my lip to keep from laughing now. But, I knew that laughing was out of the question.
"The same place you do" I replied.
"Oh." -short pause- "You wanna build a train track with me?"
"I'd love to!" I answered as I sighed with relief.