He keeps us laughing

I've hesitated to teach my children the proper names for anatomical parts because at a young age they don't understand that some things shouldn't be shouted in public or shared in casual conversation with strangers. The following story made my withholding the information all worthwhile.

We were all sitting at the dinner table when Eli left in a rush to use the bathroom. From the bathroom he called out to me that the water was too cold. I went to help assist him and upon returning to the dinner table I commented

"Eli must be the only child who washes his hands before he goes to the bathroom."

Apparently he heard me because he shouted back to us all:

"I HAVE to or else my peeing thing will get dirty!"

I thought about explaining to him that it is generally accepted by society that the "peeing thing" is inherently dirty and therefore hands should be washed after going potty, but I couldn't because I was laughing too hard.