The King (1968)

Linda is a closeted secretary living in New York City who first seduces her female boss Miss Turner. Returning home after work, Linda allows herself to be dominated by her ultra-butch girlfriend 'King' Mickey. Later, Linda, Mickey and their roommate Joan go out on an excursion to a local beach for some more fun, smoke some weed, and have a threesome leading them to a vacant apartment that happens to be owned by Miss Turner, who is not pleased at Linda showing up there.