In sex with multiple partner, 'hammerfisting' refers to the act of inserting ones fist into the vaginal- or anal orofice of a sex partner, whilst another sex partner repeatedly pounds the elbow of the inserted arm to create a hammer-effect.
by Mushroom Koen, bassmastah P June 06, 2011
to hit something or someone with a closed fist in an overhand motion intending to cause damage, similar to the way a hammer is swung using the tricep muscle. Usually quick and repetitive.
Brock Lesnar landed some mean hammerfists against Frank Mir.
"Quit being stupid before I knock you down and hammerfist your face!"
"Quit being stupid before I knock you down and hammerfist your face!"
by Forrest Griffin January 16, 2010
by messseduppp March 07, 2009