If men menstruated instead of women

Menstrual leave would be legally required and automatic. Sports teams would use birth control pills to synchronize their cycles, and would play a three weeks on, one week off schedule. Many fans would also synchronize to their teams.

Like all differences between the sexes, it would be emphasized. More flow would be manlier. More frequent flow would be manlier (and they'd take more frequent blood leave, for sure). They'd brag about it. “Hey dude, your bloodrage is coming, are you going to go with your already-stained jeans?” “What, every pair of jeans I own, you mean?”

There wouldn't be “masculine hygiene” products. They'd be Man Time, Crimson Tide, or Mighty Flow products. They'd have sports figures and trucks pictured on the packages and have names like “Blood Dam” and “Flow Caisson”. Products wouldn't have tame names like “tampon” or “sanitary napkin”, but be “flow blockers”, “blood sponges”, “grunt pads” and the like. They'd be heavily subsidized, available everywhere, and right in the front of every store with liquor and chocolate (no man with cramps should have to wend his way to the back of the store to get his monthly supplies).

Men would brag about how fast they could finish with their flows by flexing their mighty uteri (but still have excuses to always take all five days of flow leave).

Kegeling would be an Olympic sport.

PMS (pre Man-Time Syndrome) would be an excuse for … everything.

Women would be mocked for not menstruating (“Frail females couldn't deal with this amount of pain and STAND, let alone function, especially while losing QUARTS of blood EVERY DAY.”)

When no one was looking, menstruating men would just sob in the dark, bemoaning their horrible, unfair fate and popping Virodol® (Midol + Vicodin) like candy.

There would be round-the-clock ice cream delivery.

“Man cave” would have an entirely different meaning.