bromenstrual Share definition Flag adj: when a bro is cantankerous, pissy and overly-sensitive:, aka "acting like a bitch" because it is his time of the month Ryan is mad bromenstrual today, I'd ask for your headphones back later. bromenstrual by MedicMilestone November 8, 2015 0 0 Get merch Get the bromenstrual mug. Buy Now — $32.95 See more merch