What would happen, for instance, if suddenly, magically, men could menstruate and women could not?

The answer is clear - menstruation would become an enviable, boast-worthy, masculine event: men would brag about how long and how much … military men, right-wing politicians, and religious fundamentalists would cite menstruation (“men-struation”) as proof that only men could serve in the Army (“you have to give blood to take blood”), occupy political office (“can women be aggressive without that steadfast cycle governed by the planet Mars?”), be priest and ministers (“how could a woman give her blood for our sins?”) or rabbis (“without the monthly loss of impurities, women remain unclean”) … TV shows would treat the subject at length. (“Happy Days”: Richie and Potsie try to convince Fonzie that he is still “The Fonz,” though he has missed two periods in a row.)