Promises! Promises! (1963)

Synopsis
Jayne Mansfield bares almost all (and became the first Hollywood actress to do so) in this nearly universally panned sex comedy from the early 1960s. In the story, poor Sandy is desperate to get pregnant. Unfortunately, her husband, a television script writer, is too wound up over his high stress job to make love to her at night even though he too, wants a child. To help him loosen up, they go on a relaxing cruise and meet another couple. The foursome hit it off and begin drinking heavily. They soon exchange partners and retire to their rooms. Later both wives show up pregnant, but now the question remains: which baby belongs to which father? ~ Sandra Brennan, All Movie Guide