In football, when a player hits another player so hard, that the player who was hit has snot literally knocked out of his nose. More common in the winter when people tend to have colds. Sometimes called a "slobber knocker".
by Augie September 7, 2003
Get the snot knockermug. by Scrotie_McBoogerballs September 28, 2011
Get the snot knockermug. 