Big Girl

Today Penny was helping me fold diapers and she sat down on the bed up against the headboard between our pillows and said, "SIt big girl." Roughly translated, I believe she meant, "look at me. I'm sitting like a big girl." Now, since Penny is not around other kids all that much, I doubt very seriously that she knows what a "big girl" is. I think that's a word (or, rather, words) without a referent for her. But, whatever a "big girl" is, I'm sure it must seem like something important to be since we say stuff like, "sit in your chair like a big girl."