A girl who shows an extremely opposite side of herself to outsiders, such as classmates, and coworkers.
On the inside she is completely opposite and little to none know her true colors.

When you eat dirt for the first time and leave your family to build a shack in the woods

A pre-op male-to-female trans-sexual who can switch between female and male roles in sexual encounters.

Sometimes also known as 'shemales', although shemales are purely a creature of the porn world.

Note - Not ALL pre-op male-to-female trans-sexual are, or even want to be, Switch Girls (and are not 'shemales'). The average M2F (male to female) TS (trans-sexual) just wants to behave and be regarded like a natal female, whether it be in bed or out and about living normally.