1. A good looking young lady who possesses a rather grotesque vagina.
2. Someone with undesirable physical, mental or social qualities, much like an old lady's vagina.
Youth #1: Shit dude i wouldn't wind getting in Stacey
Youth #2: Nah you dont wanna do that, she's a Grannyfanny.
Enraged Driver: Piss-off ya Grannyfanny!