A person who doesn't have blond hair, but they are truly a "blond" person on the inside.
"OMG...I just remembered my story. Okay, so one day my mom's college roomate's sister's son tripped over a root when he was running. He fell over and got really scraped up. Okay...that's my story!!!" the brunette Kathryn says as a huge smile spreads across her face.
Mary Bowden and Molly look at one another and say, "Oh Kathryn you are such an inner blond."