shroom slap Share definition Flag A shroom slap is when someone uses their dick to slap someone across the face, leaving an imprint looking like a shroom on their face. Dude, guess what?! Getz told me that Jeff gave this one guy a shroom slap on the bus! shroom slap by ALF June 22, 2004 0 0 Get merch Get the shroom slap mug. Buy Now — $32.95 See more merch