Mythbusters, for men

1. Going to the zoo while menstruating will not cause apes and monkeys to attempt to escape and gang rape us. If they were that sensitive to the cycles of other species, they'd go batshit every time any other animal in the zoo came into heat. And speaking of heat, it's pheromones released during that time that drive the males of certain species wild. Male dogs don't swarm the yard because Fifi smells like blood, but because Fifi smells like the doggie version of Axe body spray, for at least a couple weeks after bleeding stops.
2. We can swim in the ocean with a tampon without attracting sharks. See, menstruation isn't actually blood, and there isn't really a lot of it; it just looks like it. It's actually (prepare yourself here) liquefied uterine tissue, and only a few ounces a month. The uterus grows a think inner layer every month which then melts/disintegrates and then just sort of leaks out slowly. It's gross, but it's not blood. I suppose if a woman were wearing a full maxi pad and were dropped into an existing circle of hungry sharks, she might attract more attention than usual, but a few drops of vaguely blood-colored tissue isn't likely to bring sharks from miles around right up to the beach. They'll stay out where they are and keep eating sea lions.