To have a firm grip on ones cock and sucking them off with your knuckle's bulging out of your hand to show your hard work.
by Insane V April 2, 2004
Get the Knuckle Downmug. "...there's a good chance ya ass is either gon' get shot, stabbed, or knuckled down, one out of the three." - Prodigy of Mobb Deep (The Infamous Prelude)
by GSTWN May 28, 2007
Get the knuckled downmug. by WoWer142 September 22, 2015
Get the knuckles downmug. to have sex
by long strongrod December 8, 2010
Get the beef knuckle beat downmug.