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.
1. Duke Nukem: I've got balls of Steel.

2. Dude: Hey you know what the "Balls of Steel" pill does in TBoI?
Other dude: i think it adds 2 soul hearts

3. Boy: I'll be asking the menacingly looking man's daughter out.
Other boy: Man, you've got Balls of Steel!
by Maxicat0 March 05, 2021
Get a Balls of Steel mug for your bunkmate Günter.
The ablility to fight somone by dragging your balls across thier face repeatedly.
by shinymantle July 08, 2014
Get a balls steel mug for your mate Helena.