A boy runs into a busty woman and they swap bodies after which He agrees to take her place at her job as a secretary. Discovering that she works for his father the boy (in the woman's body) ends up having to have sex with his father in order to maintain his new identity.

This is not really gender bender, it's just a body swap.

Base +5, Johnny_Devo -4, tudjin -6, rockball -6