The Layout (1969)

Pam runs a successful interior design business, and shares her luxurious pad with her business partner Wendy. The sexually adventurous Wendy is carrying on an affair with Rob, their building contractor. Rob's wife decides to turn the tables by seducing the normally staid Pam, reminding her of their prepubescent experiments. Pam's cousin, with whom she also played naughty schoolgirl games, shows up to visit with her Honduran roommate in tow. Finding a lack of redblooded men in town and upset by Pam's haughty attitude, her cousin devises a surprise all-girl "coming out party" to expose her supposed hypocisy.