SymPMS Share definition Flag sympathy-PMSing, when your male significant other begins to exhibit synchronously the symptoms of your premenstrual syndrome. My girlfriend is starting her period soon and now I feel bloated. I think I am symPMSing. SymPMS by oom7ggoom7 August 15, 2012 0 0 Get merch Get the SymPMS mug. Buy Now — $32.95 See more merch