knuckled down 

to physically beat someone down with your fists

"...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)

knuckled down by GSTWN May 28, 2007

Knuckle Down 

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.

Heather popped a vein in her hand after she knuckled down hard on Mikie!!!

Knuckle Down by Insane V April 2, 2004

knuckles down 

Sly way of saying jerking off.

I was knuckles down crushin my beef.

knuckles down by WoWer142 September 22, 2015

beef knuckle beat down 

to have sex

Remember that girl from biology class? I totally gave her the ol' beef knuckle beat down.

beef knuckle beat down by long strongrod December 8, 2010