Caption by Chastebob. Picture sourced from Imagefap.

I have been fascinated by the idea that the wife's mother might have some sexual control or needs that must be met in the relationship. Oddly it isn't a fantasy born of real life - both of my mothers-in-law were not women I had sexual fantasies about. But at least one (if not both) I can easily imagine holding a whip or a cane.