Jack n' Jill of the Third Kind (1978)

Despite being siblings, Gorio and Benita rarely see eye to eye. For the queer Gorio, thinks of nothing else but to be the perfect woman, while the boyish Benita, constantly rejects Gorio's senseless fantasies. Considering Gorio a hopeless case, Benita poses as a man and takes on the job as a driver to the rich playboy Raul. But then, Benita is faced with another dilemma when she finds herself falling for the charming Raul. And to make matters worse, Beinta learns of Gorio playing the role of a mysterious lover to Raul's grandfather. What will Benita and Gorio do to avoid getting caught?