1. Definition of being strong, rude and super brave, and referencing the male balls because the harder they are, the manlier the man is.
2. Having your balls masked in steel, or having your balls made of steel.
Wrapping plastic around your balls then having your sister/roommate/friend/person and then smashing your balls with a hammer while you watch Spongebob.
Guy1: "hey man are you masochist?"
Guy2: "maybe, why?"
Guy1: "My girlfriend wants to do The Steel Balls"
Guy2: "Say yes and get ready to have the time of your life"*whispers to self* or lose your manhood
Guy1:"What"