Boys' Night Out (1962)

Fred, George, Doug, and Howie are quickly reaching middle age. Three of them are married; Fred is divorced. Craving something different from their ordinary marriages, children, and TV dinners, they secretly get themselves an apartment with a beautiful young blonde, Cathy, for romantic rendezvous. But she does not tell them that she is a sociology student researching the sexual life of the white middle-class male.