Now, however, I know. I love when I have an "insider" who is willing to share the evidence - thanks Nancy!
Apparently, they practice peeing outdoors.

Walk through creeks that are deeper than their rubber boots.
Welcome to our blog. Here you will hear about our day to day life - some days more entertaining then others I guarantee. Enjoy!

Mike brought the boys and said it was just adorable. Brett went in and sat in a teeny tiny chair, put his hands on his lap and waited. Colton said he sat by him in group so that he wouldn't be scared. When I picked him up, I peeked in the window to see how he was doing. He was sitting very nicely smiling and looking at the teacher. When the door opened, he continued to sit there just waiting as though he didn't want it to be over. Adorable. He saw me and immediately asked me if I liked his crown.......the crown he didn't take off all day.
However, this past Sunday, he wasn't quite as excited. He thought it was a one time deal. His exact phrase was, "I don't have to go, I went yesterday." Everything is yesterday in his world. In the end, he went and loved it.
Nice work babe. Looks like we'll be able to eat this weekend. ;)
The kid talks to them as if they were soft, fluffy kitty-cats. "Oh, come here little grasshopper, you are so nice, I won't hurt you, I want to hold you."