My Friend Barbara (1937)

Barbara's family is poor and she needs to come up with a way to pay the gas bill. At her job in a cinema she listens to the conversation of a cheating wife and her affair. Barbara offers the husband of the cheating wife, a wealthy chemist, to help him get his wife back. Her plan is a bizarre sharade in which Barbara plays the role of the chemist's affair to make his wife jealous. Of course, this backfires in every way imaginable.