The underwear didn't go on until after naps, around 5. In the next 4 hours of his awake time, I cleaned up two puddles on the floor (thank goodness for hardwood floors) and put three pair of wet underwear in the dirty clothes. I stayed on top of him asking if he needed to go potty, but he never answered yes, and always peed on the floor :s I'm not sure if he just doesn't understand the feeling yet, or he just doesn't pay attention to it. We'll try again tomorrow since we'll be home all day. I only have 6 pair of underwear, so we might be done halfway through the day.
The other part of this story is Chaetun. He was excited for Xadun to get underwear and understood that he wasn't getting any. When we got home and I found that the Cars were too big for Xadun, I told Chaetun he could have them. Of course it wasn't enough just to have them, he had to wear them. I told him he could not change his underwear just to wear cars. He would have to wait until tomorrow. So, he proceeds to pee in them a little so that they're wet and he can take them off. I told him he would have to live with wet underwear because he knows better. He then peed a little more so as to make his pants wet wanting to change everything. Again, being the mean mom that I am, I told him he had to keep the wet underwear and pants and he would not be allowed to change. I know, I'm mean, but I'm not going to let him change his underwear just because he got new ones. :P