Moohorn Share definition Flag 1. A cow with horns. 2. A complete and utter reebo. 3. a ginger, 5ft+ guy. mark: look i can eat rubbers. nathan: shut up you moohorn. Moohorn by nathasauras and markasuarus April 13, 2009 0 0 Get merch Get the Moohorn mug. Buy Now — $32.95 See more merch