m/m is an abbreviation used in spanking art to signify an artwork or story that features a minor male spanker and a minor male spankee. In other words, a boy spanking another boy. It could be, for example, a boy spanking his playmate, another boy from his school, his brother, or his cousin. It could also be one putto spanking another.
m/m is boy spanking art.
A naked boy is birched by another boy, etching from a school book (1785).