It's common for women to want to be desired sexually, like men want to be seen as competent. It's common for small women to be treated like children instead of adults.
When you combine these two, you get Beebs. Small woman who wants to be sexually active but is constantly treated like a child who "nobody" wants to have sex with.
Corollary: People who are small and unthreatening often get away with significantly more (socially) than people who appear threatening. A small woman could literally pull a gun on you and the only question in people's minds would be "what the hell did you do wrong?". A sexually repressed tiny woman is allowed to act out considerably more than say Mori.
