verb.: An action typically seen performed by enraged apes who run with their fists closed when moving to attack someone: hence "knuckle" running. Buldging eyes and bared teeth are also commonly part of this reaction.
Also used to describe a human in a state of rage that is comparable to an angry ape.
"You're in for a bad day: John came knuckle-running into the office twenty minutes ago bellowing something about you forgetting half of the prices you were supposed to add to that quote you were working on."
Him: "So, how would your mom react if I stayed the night?"
Her: "She'd be fine. Dad would knuckle-run you right off of the property, though."
Him: "Ah. I'll go home."
Her: "Good plan."