What is “Pillow Talk Privilege”?

Wisconsin law protects spouses from having to testify to incriminating information their spouses tell them in confidence. This is because of something referred to as the “pillow talk” privilege. For example, a wife does not have to testify that her husband confessed to committing a crime. In fact, that husband can prevent this – in many but not most situations. There are important exceptions. If the wife or the children are victims of a crime, that privilege does not apply. There was also no privilege for such communications between spouses who’ve committed the crime together. This privilege exists to encourage spouses to be completely open with each other when speaking confidentially to each other. It is not to protect somebody from being prosecuted for a crime—those two competing goals of our society clash here.

https://docs.legis.wisconsin.gov/statutes/statutes/905/05