Several TV networks have agreed to air an underwear commercial portraying a surreal world where men and boys menstruate. The ad opens with an anguished young teenage boy sheepishly telling his dad, “I think I got my period.” Dad later hugs him and tells him, “It’s just part of growing up.” Many of the nine rapid-fire vignettes in the one-minute, 20-second ad are jarring: a man rolls over in bed, revealing blood-stained sheets; in a public bathroom, a man passes a tampon to another beneath a toilet stall partition; and a man walks through a locker room with a tampon...