Pee on a tree?

We visited Grandad and Grandmom(Matt's parents) for the past 5 days. They helped us with the boys so Matt could have a break and I could continue healing. Jonas has been potty training for week and a half now. He is doing so well. While we were there in their cabin in the woods, Matt gave him the option to pee in the potty or outside on a tree. He chose the tree but as he was standing there waiting, Jonas asked "pee on a tree?" As soon as Matt gave him the ok, Jonas went. Every time after that, he would run outside to pee on a tree. He loved it! I have a photo on Nancy's camera of him peeing...I will post it later when I download it. Until then, we have been so surprised and proud of Jonas' accomplishment. Last night was the first night without a diaper and he did it! He woke up and went straight to the potty. Amazing! He is so happy to be a big kid.