Daddy, what's this?

It was another one of those precious kid moments.

"Daddy, what's this?"
"What's what, Noah?"
"This thing. What's this thing inside me?"
He came up to me holding the his skin tightly around one of his testicles.
"That. What's that?"
Trying to remain calm and matter-of-fact, "Oh, that's one of your testicles."
"Oh?"
Trying not to laugh, snort or chuckle,"Uh, yeah. They're called testicles. You have two of them."
There was a brief hesitation upon further inspection.
"Um, I wouldn't exactly do that if I were you."
"Do what?"
"Uh, um, uh, squeeze them like you are doing?"
"No? Why not?"
"Doesn't that hurt?"
"No."
"Well, you remember when you accidently hurt Daddy right there?"
There was a tacit look of vague acknowledgement.
"And it was really painful?"
Nodding head.
"That's why. You should take care not to hurt your testicles becasue when they hurt, they really hurt."
He gives me a look of the kind of acceptance that you get when someone tells you something you have never really experienced but you take it on advisement.
"Trust me. That is why I get kind of protective if you put your foot or knee in that area and tell you strongly not to do that. OK?
"OK."
"Good."