You Can't Fool Your Wife is a 1940 American comedy film directed by Ray McCarey and written by Jerome Cady.

The film stars Lucille Ball, James Ellison, Robert Coote, Virginia Vale, Emma Dunn and Elaine Shepard.

Their marriage is not helped by Clara's opinionated mother living with them in their small one-bedroom apartment.

Her wish takes an unexpected turn when Andrew, at work, is assigned to show the visiting Mr. Battingcourt Jr. - the younger half of the head of their London office and who is the majority shareholder of their accounting firm - a good time while he's in the US.

Complications ensue when others find out about Batty's scheme and when Mercedes Vasquez, who looks extremely alike to Clara, also attends that party leading to a few mistaken identities.