curtain lectures
A wife's reprimands to her husband, conducted in private. Honey, you know I hate to give you curtain lectures, but can you please call when you're going to be late, so that our dinner isn't cold?
curtain lecture
A reprimand that a wife gives her husband. “Curtain” refers to the drapery on canopied beds; the image is that of a wife giving hubby a piece of her mind in the privacy of their bedroom.