I Sick

Heading home from a church meeting tonight, Tavin was making all sorts of noises-sniffing, breathing really heavy, etc.
Brett jokingly said, "Tavin, you don't sound like you're doing too good!"
"No, I not good...I sick."
We started laughing and told him he wasn't sick. He got mad at us and again claimed he was sick.
Brett said, "Oh, that's too bad cause if you're sick you have to go night-night. Are you still sick?"
"No, I not sick. I all better."
We laughed so hard. Where do kids come up with this stuff?