Your Sister?

I talk to my sister on my way to work almost every morning. She lives in PA so it is our only time we get to spend together - on the phone. Sometimes when I call her youngest answers and we catch up on the important stuff like how far he is in his Star Wars Wii game, what he is watching right now, how he tormented his parents last night - you know important stuff. The other day when I called she had to run and take him to school so we hung up from her house phone and immediately got on her cell. In this pause of conversation between us this is what went down at her house

Jared - Was that Lorinda?
Mom - Yes, and it is Aunt Dinda to you
Jared - But you call her Lorinda
Mom - Yes I do because she is my sister
Jared - SHE'S YOUR SISTER!!!!!????!!!!!

I guess I didn't realize he never knew that.....