Grumpiss Share definition Flag When you see a friend acting both grumpy and pissed. Call them Grumpiss and it will put a smile on their face! "Hey, are you Grumpiss" "HahHa what is a Grumpiss"" you mutherfucker " Grumpiss by anonymous June 4, 2016 0 0 Get merch Get the Grumpiss mug. Buy Now — $32.95 See more merch