"
She can lock and unlock it by positioning the hands of a tiny clock on the front of the garment, sort of like a gym code combination."
This might deter a drunken frat boy, but if the wearer were threatened on the street with a deadly weapon, she'd probably give up the combination pretty quickly to save her life.
Also, it would be very uncomfortable if the locking mechanism broke and the wearer couldn't use a toilet until they could find someone with the right tools to break the lock. (Imagine calling a locksmith and having to explain this problem.)
