How do you know she's a girl?

Tonight my nephew Jack came for a visit. We haven't seen him in a long time. He came over and ate dinner with us and then we did homework. For reading, he had to read a story, so he read it to Jane Baird (how sweet!) Later I gave him a bath and dried his hair so he would be all ready for bed when he got home. Anyway we had a funny conversation (keep in mind he is 6 yrs old)... Jack: Hey Meme, how do you know Jane Baird is a girl? Me: Well, how do you know you are a boy??? Jack: Because I look like a boy and talk like a boy...Jane Baird can't talk yet and she has short hair like a boy. Later in the evening... Jack: Hey Meme, can I help you give Jane Baird a bath? Meme: Sure. Let me get the water ready and then we can bathe her. Jack: Good! I want to see her naked! Jack walks in while she is in the tub and looks her over real good. Jack: Ummm, how does she tee tee? Too funny!!!