How to be Big, Little at the Same Time

Early Sunday morning, she hopped into my bed and started nuzzling him.

While hugging and smothering him with kisses, she asked in a high pitched voice "Do you want your little, big sister?""
Baby smiled and wriggled.
Big sister asked "Do you want your little, big sister?"
Baby smiled and wriggled some more.
My cutie pie asked the same question over and over again, in the same high pitched voice only a four year old can make and still sounds adorable.    

I am thinking to myself "little, big sister?"  I am confused but watched the interaction with enjoyment.  Then, I understood what she was saying; she meant that she is my little girl and his big sister.