The Key to Sex (1999)

When brainy office assistant Simon is left in charge of the boss's Hollywood mansion, the weekend becomes an opportunity of a lifetime. Entrusted by power-hungry movie producer Alan to guard the estate, Simon thinks he's finally made the grade until he learns that his friends and co-workers have their own plans for the place. The front entrance soon resembles a revolving door as a series of erotic escapades unravel before his eyes. But unassuming Simon soon finds himself living out his own fantasies in this whirlwind of sex. Alan's drop-dead gorgeous girlfriend, Christy, powerful agent Tina gives him the biggest surprise of all. Indeed, the key to sex for Simon turns out to be the key to his boss's house.