Eat, Drink and Make Merrie (1969)

Set almost entirely inside a boarding house in a nameless Texas city, Merrie (Judy Farr) is the landlord who rents out sex to others in her establishment. Merrie is currently having an affair with a married man named Edward (Artie Brooks) who has daily trysts with her while his wife is at work. Other residents whom include a horny couple, a pair of lesbians, and a pair of thrill-seeking college guys who try any way to get laid. Renee (Adrianne) is Merrie's younger sister who keeps guard over the boarding house under an alarm gong. She mostly stays out of the romps with the residents until everyone gathers for the big Saturday night Christmas party which immediately turns into one big night-long orgy in which Adrianne decides to finally get into the action and decides to seduce her sister's beau Edward.