Hammer-fist / Hammer fist

Noun (hammer fist): a striking technique where the attacker's fist is clenched, and the force is applied with the side part of the hand instead of the knuckles

Verb (hammer-fist): the act of performing a hammer fist

Khabib performed a ground-and-pound, taking the other guy to the ground and hammer-fisting the shit out of him.

(Including "hammer-fist / hammer fist" in parentheses because the Urban Dictionary won't let me publish it unless it's said here and I don't feel like using that whole phrase in the example.)